McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
1. Trigonometric Functions in Right Triangles
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Exercise 51 Page 797

Use the tangent ratio to find a.

m∠ A = 59^(∘)
a = 31.6
c = 36.9

Practice makes perfect

Let's analyze the right triangle that satisfies the given conditions.

We will find the missing measures one at a time. In this case, this means that we want to find m ∠ A, a, and c.

Angle Measure

To find m∠ A, recall that the acute angles of a right triangle are complementary. Therefore, m ∠ A and m ∠ B add to 90^(∘). m ∠ A + m ∠ B = 90^(∘) Now, we can substitute the measure of ∠ B in our equation and find the measure of ∠ A. m ∠ A + 31^(∘) = 90 ^(∘) ⇔ m ∠ A = 59^(∘)

Side Lengths

We will find the length of the leg adjacent to the 31^(∘) angle. We are given the length of the leg opposite to this angle. Therefore, we will use the tangent ratio. tan θ = opposite/adjacent In our triangle, we have that θ = 31^(∘) and the length of the opposite leg is 19. We want to find the length of the adjacent leg.

tan θ = opposite/adjacent
tan 31^(∘) = 19/a
â–¼
Solve for a
tan 31^(∘) * a = 19
a = 19/tan 31^(∘)
a = 31.62131...
a ≈ 31.6

To find the value of c, we can use Pythagorean Theorem. a^2 + b^2 = c^2 Let's substitute the known lengths, a = 31.6 and b = 19, into this equation to find c.

a^2 + b^2 = c^2
31.6^2 + 19^2 = c^2
â–¼
Solve for c
998.56 + 361 = c^2
1359.56 = c^2
sqrt(1359.56) = c
c = sqrt(1359.56)
c = 36.872211 ...
c ≈ 36.9