Answer:
The answer is below
Step-by-step explanation:
If you want to find the hypotenuse, your equation is right, but the next step is wrong
sin 39 = 20/c
c = 20/sin39 = 20 / 0.63 = 31.74
If you need to find b you need to use the pythagorean theorem
c2 = a2 + b2
b2 = c2 - a2
b2 = 31.74 ² - 20² = 1007.4 - 400
b2 = 607.4
b = 24.64
