McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
4. Trigonometry
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Exercise 15 Page 655

Use the sine ratio to find m ∠ R.

m ∠ R ≈ 42
m ∠ T ≈ 48
RS ≈ 6.7

Practice makes perfect

Let's analyze the given right triangle.

We will find the missing measures one at a time. In this case, this means that we want to find the measures of ∠ R and ∠ T, and the length of the segment RS.

Angle Measures

We can find m ∠ R using a sine ratio.
The sine of ∠ R is the ratio of the length of the leg opposite ∠ R to the length of the hypotenuse. Sine=Opposite/Hypotenuse ⇒ sin R =6/9 By the definition of the inverse sine, the inverse sine of 69 is the measure of ∠ R. To find it, we have to use a calculator.
m∠ R=sin ^(-1) 6/9
m∠ R = 41.810314
m ∠ R ≈ 42
To find m∠ T, recall that the acute angles of a right triangle are complementary. Therefore, m ∠ T and m ∠ R add to 90. m ∠ T + m ∠ R = 90 Now, we can substitute the rounded measure of ∠ R in our equation and find the measure of ∠ T. m ∠ T + 42 = 90 ⇔ m ∠ T ≈ 48

Side Lengths

Finally, we can find the measure of RS. To do it, we can use the Pythagorean Theorem. (RS)^2 + (ST)^2 = (RT)^2 Let's substitute the known lengths, ST =6 and RT= 9, into this equation to find RS.
(RS)^2 + (ST)^2 = (RT)^2
(RS)^2 + 6^2= 9^2
Solve for RS
(RS)^2+36=81
(RS)^2= 45
RS= sqrt(45)
RS ≈ 6.7082039
RS=6.7