How to find an angle in an acute / obtuse isosceles triangle

Practice Questions

PSAT Math › How to find an angle in an acute / obtuse isosceles triangle

Questions

9

1

The base angle of an isosceles triangle is 15 less than three times the vertex angle. What is the vertex angle?

2

The base angle of an isosceles triangle is five more than twice the vertex angle. What is the base angle?

3

Triangle ABC has angle measures as follows:

$\dpi{100} \small m\angle ABC=4x+3$

$\dpi{100} \small m\angle ACB=2x+6$

$\dpi{100} \small m\angle BAC=3x$

What is $\dpi{100} \small m\angle BAC$ ?

4

In an isosceles triangle, the vertex angle is 15 less than the base angle. What is the base angle?

5

If the average (arithmetic mean) of two noncongruent angles of an isosceles triangle is , which of the following is the measure of one of the angles of the triangle?

6

The base angle of an isosceles triangle is $27^{\circ}$ . What is the vertex angle?

7

The base angle of an isosceles triangle is 10 more than twice the vertex angle. What is the vertex angle?

8

The base angle of an isosceles triangle is ten less than twice the vertex angle. What is the vertex angle?

9

In an isosceles triangle the vertex angle is half the base angle. What is the vertex angle?

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