McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
4. Trigonometry
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Exercise 1 Page 655

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

16/20=0.80

Practice makes perfect

For the given right triangle, we want to write the ratio for the sine of ∠ 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 20. The length of the side adjacent to ∠ A is 12 and the length of the side opposite to ∠ A is 16. With this information, we can find the desired ratio. Recall how we calculate the sine ratio. sin A = Length of leg opposite to∠ A/Length of hypotenuse Now, we can substitute our values to the above formula to find sinA.
sin A = opposite/hypotenuse
sin A = 16/20
Finally, let's express the obtained fraction as a decimal. In order to do that, we can expand the fraction so that it has a denominator of 100.
sin A = 16/20
sin A = 80/100
sin A = 0.80
Therefore, we have that the sine of ∠ A is equal to 1620 = 0.80.