Question

Assume that lines which appear to be tangent are tangent. Find the value of the?

Answer 1

Answer:

12

Step-by-step explanation:

Assume that lines which appear to be tangent are tangent.

Therefor this is a right triangle.

Use the pythagorean theorem

c^2 = a^2 + b^2

15^2 = ?^2 + 9^2

225 = ?^2 + 81

subtract 81 from both sides

144 = ?^2

Take the square root of both sides

12 = ?

Answer 2

9514 1404 393

Answer:

  ? = 12

Step-by-step explanation:

The tangent makes a right angle with the radius at the point of tangency. That means the Pythagorean theorem can be used to find the missing length.

  ?² +9² = 12²

  ?² = 225 -81 = 144

  ? = √144 = 12

The value of ? is 12.

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Additional comment

When you see a right triangle with the ratio of hypotenuse to leg of 15:9 = 5:3, you know immediately that it is a multiple of a 3:4:5 right triangle. Here, the scale factor is 3, so the missing side is 3×4 = 12.