Question

AB = AC = 10 cm and angle A = 30° in triangle ABC find area of the triangle.

Answer 1

Area = bcSinA/2
=10*10*1/2*1/2
25 cm sq

Answer 2

Area of a triangle can be given as half the product of two sides multiplied by the Sine of the angle between them.

ar(triangle ABC) = 1/2 × AB × AC × Sin CAB
= 1/2 × 10 × 10 × Sin 30°
= 25 cm^2.

Here AC Sin CAB will be equal to the altitude from C onto AB.