Answer: D) 20/21
Step-by-step explanation:
Recall that sin(theta) = opposite/hypotenuse.
sin(theta) = 20/29 tells us that 20 is the vertical side while 29 is the hypotenuse. Note how the vertical side is opposite the reference angle theta.
Use these two sides to find that the missing side is 21. You'll need the pythagorean theorem a^2+b^2 = c^2.
Once you determine that the adjacent side is 21 units long, we can then say,
tan(theta) = opposite/adjacent = 20/21