#1
Midsegment is half the parallel side:
- 11x + 5 = 2(3x + 5)
- 11x + 5 = 6x + 10
- 11x - 6x = 10 - 5
- 5x = 5
- x = 1
- Midsegment length = 3*1 + 5 = 8
- Third side length = 8*2 = 16
#2
ORT is isosceles, the angles O and R are equal and measure:
- 1/2(180 - 72) = 1/2(108) = 54
IRN is isosceles, the angles N and I are equal and measure:
- 1/2(180 - 54) = 1/2(126) = 63°
#3
ABC is isosceles, the angles A and B are equal and measure:
- 1/2(180 - 50) = 1/2(130) = 65°
