PLEASE HELP! (If you don’t know it please don’t answer)

Which expression is equivalent to 64 - 9x^2?

Polygon abcd is a parallelogram, and m? abc = 127°. the length of is 10 units, and the length of is 5 units. the perimeter of the parallelogram is units, and m? bcd is °

Find the radius of a circle that has a circumference of 16. the formula for the circumference of a circle is c = 2tr, where r is the radius and c is the circumference. the equation solved for r is r = c over 2π. r=4 r= 8 r=12 r= 16