Help this is dealing with trigometry

In the image, point a marks the center of the circle. which two lengths must form a ratio of 1 : 2? (options are in the images since thought they were harmful phrases)

If the simple annual interest rate on a loan is 6, what is the interest rate in percentage per month?

Javier bought a painting for $150. each year, the painting's value increases by a factor of 1.15. which expression gives the painting's value after 77 years?