How to write those into an equation

Suppose the radius of a circle is 16. what issuppose the radius of a circle is 16. what is its circumference its circumference

If sec theta = 5/3 and the terminal point determined by theta is in quadrant 4, then

Use the formulas a = x 2 – y 2, b = 2xy, c = x 2 + y 2 to answer this question. one leg of a right triangle has length 11 and all sides are whole numbers. find the lengths of the other two sides. the other leg = a0 and the hypotenuse = a1