In the following figure, ΔPTQ is an equilateral triangle and PQRS is a square, the find the value of ∠STR = ?
In the following figure, ΔPTQ is an equilateral triangle and PQRS is a square, the find the value of ∠STR = ? Correct Answer 30°
Given,
ΔPTQ is an equilateral triangle.
PQRS is a square.
Formula:
Each angle of an equilateral triangle is 60°
Each angle of a square is 90°.
Calculation:
ΔPTQ is an equilateral triangle, then
PQ = PT = TQ ---- (1)
PQRS is a square, then
PQ = QR = RS = SP ---- (2)
From equation (1) and equation (2)
PQ = PT = TQ = QR = RS = SP
∠TQP = 60° and ∠PQR = 90°
Now, ∠TQR = ∠TQP + ∠PQR
⇒ ∠TQR = 90° + 60° = 150°
In ΔTQR,
⇒ TQ = QR, then
⇒ ∠QTR = ∠QRT
⇒ ∠QTR + ∠QRT + ∠TQR = 180°
⇒ 2∠QTR + 150° = 180°
⇒ 2∠QTR = 180° - 150°
⇒ 2∠QTR = 30°
⇒ ∠QTR = 30°/2
⇒ ∠QTR = 15°
Similarly,
⇒ ∠PTS = 15°
⇒ ∠PTQ = ∠PTS + ∠STR + ∠QTR
⇒ 60° = 15° + ∠STR + 15°
⇒ ∠STR = 60° – 30°
∴ ∠STR = 30°