Answer:
r = 28.28
Explanation:
you already gave the equation: sin45°= 20/r
you wanna start by multiplying both sides by r. You do this so that your variable can be in the numerator and it will be easier to solve the equation:
r (sin45°) = 20
Now you divide both sides by sin45°, this will give you your final answer. For this, you have to put it in a calculator:
r = 28.28
P.S, good job on already knowing your equation... when i was learning this it took me a while to get eh hang of it :)