How do you work out this problem

Step-by-step explanation:

So first we need to make sure we know the trig identities to solve this problem.

Here we only have two legs of the triangle, so we will need to use the Pythagorean Theorem a² + b² = c² to solve for the missing leg, the hypotenuse in this case.

Now we can use the trig identities to figure out the missing values for the problem

the correct is answer is a 9-sided polygon!