Hint, I have an idea, what we should do is to find the length of lines by using the Pythagorean's Theory of a^2+b^2=c^2 since a lot of the incomplete triangle have 2 given side lengths.
There is a theorem in geometry that states that: (8)(8 + 2) = (x)(x)
If you use the other line segment: (4)(4 + 16) = (x)(x)
Either way, you end with: 80 = x2 ---> x = sqrt(80)
You are right, geno!!!
If one secant and one tangent are drawn to a circle from one exterior point, then the square of the length of the tangent is equal to the product of the external secant segment and the total length of the secant.
x2 = 4 ( 4 + 16 )
x2 = 8 ( 8 + 2 )