How do i solve this and what's the answer? Thank you.

1.6.63 Find an equation for the graph shown to the right. Type the equation in the form y = A sin (wx) or y = A cos (wx). y= (Type an exact answer, using it as needed. Use integers or fractions for any numbers in the expression.) - 21 X 4TC 10T Enter your answer in the answer box and then click Check