In Fig. 16.177, Δ PQR is an isosceles triangle with PQ=PR and m∠PQR=35°. Find m∠QSR and m∠QTR.
We have,
∠PQR = 35o
∠PQR + ∠PRQ = 35o (Angle opposite to equal sides)
In triangle PQR, by angle sum property
∠P + ∠Q + ∠R = 180o
∠P + 35o + 35o = 180o
∠P = 110o
Now,
∠QSR + ∠QTR = 180o
110o + ∠QTR = 180o
∠QTR = 70o