Answer:
x = 5
Step-by-step 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.
