Can anyone help me please

Match the term on the left with its image or description on the right. match term definition diameter a) circle a and a line segment connecting points b and c which are on the circle. circumference b) circle a and a line segment connecting points b and c which are on the circle. radius c) a piece of the circumference of a circle secant d) two circles that share the same center. concentric circles e) the distance around a circle arc f) a segment between two points on a circle that passes through its center

Which of the following is the true for f(x) = 5cos

What is the value of x when x + 7 = 21?