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McGraw Hill Integrated II, 2012

MH

McGraw Hill Integrated II, 2012 View details

4. Trigonometry

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Exercise 10 Page 655

Determine the trigonometric ratio to use according to the given information and the unknown.

16.93

Practice makes perfect

We are given the length of the hypotenuse and the measure of an acute angle of a right triangle. We want to find the length of one of the legs.

Note that the given side is the hypotenuse, and the side we want to find is adjacent to the given angle. Therefore, we will use the cosine ratio. cos θ = Length of leg adjacent toθ/Length of hypotenuse In our triangle, we have that θ =27^(∘) and the length of the hypotenuse is 19. We want to find the length of the leg adjacent to the angle.

cos θ = adjacent/hypotenuse

SubstituteValues

Substitute values

cos 27^(∘) = x/19

▼

Solve for x

LHS * 19=RHS* 19

cos 27^(∘) * 19 = x

Use a calculator

16.92912... = x

Round to 2 decimal place(s)

16.93 ≈ x

Rearrange equation

x≈ 16.93

Subchapter links

Exercises p.655-659