After 50 years, Helena's age will be three times her age now. How old is Helena now?

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

If a || b and e || f , what if the value of y ?

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).