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 22 Page 924

Use the tangent ratio to find m ∠ B.

c≈ 10.2
m ∠ A ≈ 52.6^(∘)
m ∠ B ≈ 37.4^(∘)

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 m ∠ A, m ∠ B, and c.

Angle Measures

We can find m ∠ 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. tan A=Opposite/Adjacent ⇒ tan A =8.1/6.2 By the definition of the inverse tangent, the inverse tangent of 8.16.2 is the measure of ∠ A. To find it, we have to use a calculator.
m∠ A=tan ^(-1) 8.1/6.2
m∠ A = 52.56839... ^(∘)
m∠ A ≈ 52.6 ^(∘)
To find m∠ B, recall that the acute angles of a right triangle are complementary. Therefore, m ∠ B and m ∠ A add to 90^(∘). m ∠ A + m ∠ B = 90^(∘) Now, we can substitute the approximated measure of ∠ A in our equation and find the measure of ∠ B. 52.6 ^(∘) + m ∠ B ^(∘) ≈ 90^(∘) ⇔ m ∠ B ≈37.4^(∘)

Side Lengths

Finally, we can find the measure of c. To do it, we can use the Pythagorean Theorem. a^2 + b^2 = c^2 Let's substitute the known lengths, a = 8.1 and b= 6.2, into this equation to find c.
a^2+b^2=c^2
8.1^2 + 6.2^2= c^2
Solve for c
65.61+38.44=c^2
104.05=c^2
sqrt(104.05)=c
c=sqrt(104.05)
c=10.200490...
c≈ 10.2