McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
6. Secants, Tangents, and Angle Measures
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Exercise 48 Page 767

5sqrt(10)

Practice makes perfect

Let's start by paying close attention to the triangle in the given diagram.

Note that segment measuring 5 is a radius and the segment measuring 15 is a tangent to the circle. According to the Tangent to a Circle Theorem, the angle formed by them is a right angle. Also, the triangle is a right triangle.

We can see that the lengths of the legs are 5 and 15. The length of the hypotenuse is x. If we substitute these values in the equation of the Pythagorean Theorem, we will be able to find the value of x. Let's do it!
a^2+b^2=c^2
5^2+ 15^2= x^2
â–Ľ
Solve for x
25+225=x^2
250=x^2
x^2 = 250
x = sqrt(250)
x = sqrt(25* 10)
x = 5 sqrt(10)
We only take the positive root of x^2, since a segment cannot have negative length. Therefore, the value of x is 5sqrt(10).