An isosceles triangle has an area of 21 cm2 and the angle be

An isosceles triangle has an area of 21 cm^2, and the angle between the two equal sides is 5 pi/6. Find the length of the two equal sides. cm

Solution

Area of triangle = (a*b/2)sinC

a and b are the sides and C is the including angle

Here a and b are equal

Therefore 21=(a²/2)sin(5pi/6)

42=a²sin(5pi/6)

a²=42*2

a²=84

a=9.2cm