Answer:
15.55723827cm
Step-by-step explanation:
The sum of the interior of the triangle is 180 degrees
So 180 - 80 = 100 degrees left. Since the triangle is isosceles (2 same length) The angle left inside would be shared( ÷2 )
100 ÷ 2 = 50 degrees
50, 50, 80 degrees ----these are the angles inside. Let x be the side of the triangle.
Using the sine law.
Side1/ sin(its vertex angle) =Side2/ sin(its vertex angle)
x/ sin(50) = 20/ sin(80)
x= 20sin(50)/ sin(80)
x= 15.55723827
