#1**+3 **

there is formula for this, it is 9*(9+16) is the tangent line length squared, so 225=9x^2 so x=5.

HOPE THIS HELPED!

asdf335 Jan 26, 2019

#2**+2 **

Since this has a tangent and secant, Power Of Point gives us \(9x^2=225, x^2=25, \boxed{x=5}.\)

.tertre Jan 27, 2019

#5**+1 **

Tetre got it from (3x)^2 = 9x^2 Thanks Tertre and asdf

There is an obscure circle geometry law that says if A is a point external to the circle

then the square of the tangential distance from A to the circle

is equal to the square of the distance from A to the furthest point on any chord that is collinear with A.

Maybe that can be worded better. :/

anyway it says \((3x)^2=(9+16)^2\)

No one on this post has attempted to prove this. They have simply used it to answer your question.

Melody
Jan 27, 2019