Rhombuses - ACT Math

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Question

The two acute angles in a rhombus add up to . What is the measure of one of the obtuse angles in the rhombus?

Answer

The key here is to know that a rhombus has two pairs of congruent angles. In other words, the two acute angles of a rhombus are equal and the two obtuse angles are equal.

In this problem, since the two acute angles add up to and they must both be the same amount, each of the acute angles must be .

It is also important to know that the four angles of a rhombus add up to . If the two acute angles add up to , then that means that the two obtuse angles must add up to , or .

Finally, because the obtuse angles add up to and they must be congruent, each of the obtuse angles must be .

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Question

A rhombus has two interior angles each with a measurement of . Find the sum of the remaining two angles.

Answer

To solve this problem, consider that the sum total of the four interior angles in any rhombus must equal . Furthermore, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Since this problem provides the measurement for two of the interior angles, find the sum of those two angles. Then subtract that sum from to find the sum of the two remaining interior angles.

The solution is:

Note: this means that each of the two remaining angles must have a measurement of .

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Question

A rhombus has two interior angles each with a measurement of . Find the measurement for one of the two remaining angles.

Answer

First, consider that the sum total of the four interior angles in any rhombus must equal . Furthermore, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

One way to approach this problem is to realize that each of the remaining two angles must have the same measurement, and that each will be supplementary angles with . Find the difference between and to find the solution.

The correct answer is:

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Question

A rhombus has an interior angle with a measurement of . Find the measurement for one of the angles that are adjacent to the angle that has a measurement of .

Answer

A rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

If a rhombus has an interior angle that has a measurement of , the adjacent angle must equal:

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Question

A rhombus has two opposite interior angles that have a sum of . Find the sum of the remaining two angles.

Answer

The sum total of the four interior angles in any rhombus must equal . Furthermore, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Since, two of the opposite interior angles in this rhombus have a sum measurement of , the sum of the remaining two angles must equal:

To check your answer note:

(meaning the sum of the four interior angles equals ).

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Question

Act rhombus vt

Using the rhombus shown above, find the measurement for angle .

Answer

A rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Since this problem involves supplementary angles, the solution is:

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Question

A rhombus has two interior angles each with a measurement of . Find the measurement for one of the two remaining angles.

Answer

The sum total of the four interior angles in any rhombus must equal . Furthermore, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

One way to approach this problem is to realize that each of the remaining two angles must have the same measurement, and that each will be supplementary angles with .

Find the difference between and to find the solution.

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Question

A rhombus has two interior angles each with a measurement of . Find the sum of the remaining two angles.

Answer

To solve this problem, consider that the sum total of the four interior angles in any rhombus must equal . Furthermore, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Since this problem provides the measurement for two of the interior angles, find the sum of those two angles. Then subtract that sum from to find the sum of the two remaining interior angles.

The solution is:

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Question

A rhombus has two interior angles each with a measurement of . Find the sum of the remaining two angles.

Answer

To solve this problem, consider that the sum total of the four interior angles in any rhombus must equal . Furthermore, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Since this problem provides the measurement for two of the interior angles, find the sum of those two angles. Then subtract that sum from to find the sum of the two remaining interior angles.

The solution is:

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Question

A rhombus has an interior angle with a measurement of . Find the measurement for one of the angles that are adjacent to the angle that has a measurement of .

Answer

A rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Therefore, if a rhombus has an interior angle that has a measurement of , then the adjacent angle must equal:

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Question

Act rhombus vt

Using the rhombus shown above, find the measurement for angle .

Answer

A rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

Since this problem involves supplementary angles, the solution is:

Check answer by:

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Question

A rhombus has two interior angles each with a measurement of . Find the measurement for one of the two remaining angles.

Answer

First, consider that the sum total of the four interior angles in any rhombus must equal . Secondly, a rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

One way to approach this problem is to realize that each of the remaining two angles must have the same measurement, and that each will be supplementary angles with . Therefore, find the difference between and to find the solution.

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Question

A rhombus has two interior angles each with a measurement of . Find the measurement for one of the two remaining angles.

Answer

A rhombus must have two sets of equivalent opposite interior angles, and a rhombus must have two sets of adjacent interior angles. The adjacent interior angles must be supplementary—meaning they have a sum total of .

One way to approach this problem is to realize that each of the remaining two angles must have the same measurement, and that each will be supplementary angles with . Find the difference between and to find the solution.

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Question

A quadrilateral ABCD has diagonals that are perpendicular bisectors of one another. Which of the following classifications must apply to quadrilateral ABCD?

I. parallelogram

II. rhombus

III. square

Answer

If the diagonals of a quadrilateral are perpendicular bisectors of one another, then the quadrilateral must be a rhombus, but not necessarily a square. Since all rhombi are also parallelograms, quadrilateral ABCD must be both a rhombus and parallelogram.

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Question

Rhomboids

Are the two rhombuses in the above picture similar?

Answer

Two shapes are similar to each other if they are the same except for differences in scaling. This means that all of the angles of one shape have to be the same as the angles of the other shape, and all the sides have to be proportional to each other. For example, if we have two rectangles A and B, where A has side lengths 2 and 4, and B has side lengths 5 and 10, A and B are similar because the ratio between 2 and 4 is the same as the ratio between 5 and 10, and also the ratio between 2 and 5 is the same as the ratio between 4 and 10. Everything is proportional (and all the angles are the same) so the two rectangles A and B are similar.

The two rhombuses in our figure are not similar to each other, because we can see the larger angle in the rhombus on the left is not the same as the larger angle in the rhombus on the right. If we scaled the larger rhombus down and tried to cover up the smaller rhombus with it, it wouldn't work because they aren't proportional to each other.

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Question

A rhombus contains diagonals with the length and . Find the area of the rhombus.

Answer

The equation for the area of a rhombus is given by:

where and are the two diagonal lengths.

This problem very quickly becomes one of the "plug and chug" type, where the given values just need to be substituted into the equation and the equation then solved. By plugging in the values given, we get:

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Question

Find the area of a rhombus if the diagonals lengths are and .

Answer

Write the formula for the area of a rhombus:

Substitute the given lengths of the diagonals and solve:

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Question

Find the area of a rhombus if the diagonals lengths are and .

Answer

Write the formula for finding the area of a rhombus. Substitute the diagonals and evaluate.

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Question

If the area of a rhombus is , and the length of one of its diagonals is , what must be the length of the other diagonal?

Answer

Write the formula for the area of a rhombus.

Plug in the given area and diagonal length. Solve for the other diagonal.

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Question

If the diagonals of a rhombus were and , what is the side length of the rhombus?

Answer

Write the formula used to find the rhombus side length given 2 diagonals.

Substitute both diagonals in the equation and simplify.

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