Question

Solve for x! It's for circles, and I don't understand how to figure it out. So if someone could help, that would be great!

Answer 1

x = 5

Explanation:

The only thing the circle does for you is tell you that the angle between the lines marked 3 and 4 is a right angle. A tangent line is always at right angles to the radius at that point.

So, you have a 3-4-x right triangle. The Pythagorean theorem applies:

3² +4² = x²

9 + 16 = x² = 25

x = √25

x = 5

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Comment on the answer

This is a 3-4-5 right triangle. You will meet them a lot, so it is useful to remember these side ratios form a right triangle.