Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
Mid-Chapter Quiz
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Exercise 12 Page 514

Start by identifying the hypotenuse of the right triangle. Then find the sides that are opposite and adjacent to ∠ A and ∠ B.

Ratios for ∠ A: sin A=5/13, cos A=12/13, tan A=5/12

Ratios for ∠ B: sin B=12/13, cos B=5/13, tan B=12/5

Practice makes perfect

For the given right triangle, we want to write the ratios for the sine, cosine, and tangent of ∠ A and ∠ B.

Ratios for ∠ A

Let's start by identifying the hypotenuse of the triangle and the sides that are opposite and adjacent to ∠ A.

We see that the length of the hypotenuse is 78. The length of the side adjacent to ∠ A is 72 and the length of the side opposite to ∠ A is 30. With this information, we can find the desired ratios.

Ratio Definition Value
sin A Length of leg opposite∠ A/Length of hypotenuse 30/78=5/13
cos A Length of leg adjacent∠ A/Length of hypotenuse 72/78=12/13
tan A Length of leg opposite∠ A/Length of leg adjacent∠ A 30/72=5/12

Ratios for ∠ B

We already know the length of the hypotenuse is 78. Let's identify the sides that are opposite and adjacent to ∠ B.

The length of the side adjacent to ∠ B is 30 and the length of the side opposite to ∠ B is 72. With this information, we can find the desired ratios.

Ratio Definition Value
sin B Length of leg opposite∠ B/Length of hypotenuse 72/78=12/13
cos B Length of leg adjacent∠ B/Length of hypotenuse 30/78=5/13
tan B Length of leg opposite∠ B/Length of leg adjacent∠ B 72/30=12/5