Question

Find the value of x in the isosceles triangle below then find the measure of the base angle.

x = __°
Measure of 1 base angle = __°

Answer 1

Answer:
`x=13`, one base angle measures
`74^(\circ)`

Explanation:

The base angles of an isosceles triangle are congruent, so:

• 5x + 9 = 8x - 30 [congruent angles have equal measure]
• 9 = 3x - 30 [subtract 5x from both sides]
• 39 = 3x [add 30 to both sides]
• x = 13 [divide both sides by 3]

Hence, the measure of one base angle is
`5(13)+9=\boxed{74^(\circ)}`