Question

Circle A and circle B are congruent. CD is a chord of both circles. If CD = 16cm and the radius is 17cm, how long is AB?

a) 23 cm b) 30 cm c) 12 cm d)15cm

Answer 1

would it be 15?

Answer 2

Do you know the length of AC?

Answer 3

If you do, that is the hypotenuse of a right triangle formed by AC, 1/2 of AB and 1/2 of CD...

Answer 4

no i don't know AC

Answer 5

Are you sure? Isn't that just a radius?

Answer 6

look at rhombus ACBD

Answer 7

lets say the diagonals intersect at E

Answer 8

OK...

Answer 9

since CD = 16,

CE = 8 (why ?)

Answer 10

radius?

Answer 11

look at the pic again. E is the meeting point of diagonals.