7. In the diagram shown, PT = QT = QR.
Also, RT = RS and PTQ = 36º.
What is PTS?
A 72°, B 80°, C 90°, D 100°, E 108°
Please can anyone help me understand this question??

7 In the diagram shown PT QT QR Also RT RS and PTQ 36º What is PTS A 72 B 80 C 90 D 100 E 108 Please can anyone help me understand this question class=

Respuesta :

Answer:

C

Step-by-step explanation:

Since PT = QT , then Δ PQT is isosceles with the 2 base angles congruent.

∠ PQT = [tex]\frac{180-36}{2}[/tex] = 72°

∠ TQR = 180° - 72° = 108° ( adjacent angles on a straight line )

Since QT = QR , then Δ QRT is isosceles with 2 base angles congruent

∠ QTR = ∠ QRT = [tex]\frac{180-108}{2}[/tex] = [tex]\frac{72}{2}[/tex] = 36°

∠ TRS = 180° - 36° = 144° ( adjacent angles on a straight line )

Since RT = RS , then Δ TRS is isosceles with 3 bas angle congruent

∠ RTS = ∠ RST = [tex]\frac{180-144}{2}[/tex] = [tex]\frac{36}{2}[/tex] = 18°

Then

∠ PTS = ∠ PTQ + ∠ QTR + ∠ RTS = 36° + 36° + 18° = 90°