Find the circumference of a button with a radius of 21 mm use 3.14 for

What is sin 7x/4 ? i need on this urgent trig

Adecorative window is made up of a rectangle with semicircles at either end. the ratio of ad to ab is 3: 2 and ab is 30 inches. what is the ratio of the area of the rectangle to the combined area of the semicircles? possible answers: a. 2: 3 b. 3: 2 c. 6: π d. 9: π e. 30: π

M. xyz =radians. covert this radian measure to its equivalent measure in degrees.