Step-by-step explanation:
two secants in a circle originating from the same point.
then the product of outer length and total length is the same for both.
8x(8x+6x) = 7×(9+7)
8x × 14x = 63 + 49
112x² = 112
x² = 1
x = 1
(x - 3)(x - 3 + 16) = (x + 3)(x + 3)
(x - 3)(x + 13) = x² + 6x + 9
x² + 13x - 3x - 39 = x² + 6x + 9
x² + 10x - 39 = x² + 6x + 9
4x = 48
x = 12
MN = x + 3 = 12 + 3 = 15
