Pearson Algebra 2 Common Core, 2011
PA
Pearson Algebra 2 Common Core, 2011 View details
3. Right Triangles and Trigonometric Ratios
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Exercise 41 Page 925

Use the tangent ratio to find a.

a≈ 3.9
c≈ 6.9
m ∠ B =55.8^(∘)

Practice makes perfect

First, let's draw the measurements from the exercise on a right triangle to visualize the given information.

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

Side Lengths

We can find a using a tangent ratio. The tangent of ∠ A is the ratio of the length of the leg opposite ∠ A to the length of the leg adjacent ∠ A. We know that a is equal to the length of the leg opposite ∠ A and that 5.7 is equal to the length of the leg adjacent ∠ A. Therefore, we can write the following equation. Tangent=Opposite/Adjacent ⇒ tan 34.2 ^(∘) =a/5.7 To solve this equation, we will first isolate a. Then, we will have to use the calculator to find the value of tan 34.2 ^(∘).
tan 34.2 ^(∘) =a/5.7
Solve for a
5.7(tan 34.2 ^(∘)) =a
a=5.7(tan 34.2 ^(∘))
a=5.7(0.67959...)
a≈ 3.873716
a≈ 3.9
Now, we can find c using the Pythagorean Theorem. a^2 + b^2 = c^2 Let's substitute the known lengths, a = 3.9 and b= 5.7, into this equation to find c.
a^2+b^2=c^2
3.9^2 + 5.7^2= c^2
Solve for c
15.21+32.49=c^2
47.7=c^2
sqrt(47.7)=c
c=sqrt(47.7)
c=6.90651...
c≈ 6.9

Angle Measures

To find m∠ B, recall that the acute angles of a right triangle are complementary. Therefore, m ∠ A and m ∠ B add up to 90^(∘). m ∠ A + m ∠ B = 90^(∘) Now, we can substitute the measure of ∠ A in our equation and find the measure of ∠ B. 34.2^(∘) + m ∠ B = 90^(∘) ⇔ m ∠ B =55.8^(∘)