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(given an isosceles triangle find the perimeter of ABC and the measure of the missing angle. A 4x + 12 B 4x+ 12 C 2x+ 15

(given an isosceles triangle find the perimeter of ABC and the measure of the missing-example-1

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Given that the triangle is isosceles, then ∠A is congruent to ∠B

The addition of the three angles of a triangle is equal to 180°, then

∠A + ∠B + ∠C = 180°

∠A + ∠A + 132° = 180°

2∠A = 180° - 132°

∠A = 48°/2

∠A = 24°

and

∠B = 24°

Given that the triangle is isosceles, then side AC is congruent to side CB, that is,

AC = CB

2x + 15 = 4x - 5

15 + 5 = 4x - 2x

20 = 2x

20/2 = x

10 = x

Therefore, each side measure:

AC = 2x + 15

AC = 2*10 + 15

AC = 35

CB = 4x - 5

CB = 4*10 - 5

CB = 35

AB = 4x + 12

AB = 4*10 + 12

AB = 52

Finally, the perimeter of the triangle is

P = AC + CB + AB

P = 35 + 35 + 52

P = 122

User Lee Warnock
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