Answer:
If what you are doing here is trying to get the value of x then:
Those two lines passing through the circle are secants.
Now, a formula I was taught in class is:
(outside)(whole) = (outside)(whole)
**1 SEGMENT'S VALUES PER SIDE** **DO NOT MIX**
"Outside" represents the value of the segment which is found outside of the circle.
The "whole" would be the outside segment plus the inside segment.
Thus, the formula would be:
(4)(9+4) = (x)(x + 12)
Next, you would simplify by adding, multiplying, and doing the distributive property:
(4)(13) = (x)(x + 12)
52 = x² + 12x
In this case, you would have to use the quadratic formula, while at other times, you could simply move around the terms and get the square root of a number.
Set the equation to zero:
x² + 12x - 52 = 0
Next plug-in the values
(-b (+ or -)√b² - 4 (a)(c) )/ (2)(a)
(-(12) (+ or - )√12² - 4(1)(-52)) / (2)(1)
(-12 (+ or -) √144 + 208) / 2
(-12 (+ or -) √352) / 2
Now, the square root of 352 would be approximate, since 352 is not a perfect square.
352 is approximately 18.7616630393 or, when rounded to the nearest hundredth, 18.76.
So.....
(-12 (+ or -) 18.76) / 2
Solve for both the + and the -
(-12 + 18.76) /2 = (approximately) 3.38 = x
(-12 - 18.76)/2 = (approximately) -15.38 = x
Therefore, x would be equal to 3.
