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 49 Page 797

Practice makes perfect
a We are given a diagram that represents a falcon at a height of 200 feet that sees two mice A and B.

We will find the approximate distance z between the falcon and mouse B.

We will write an equation using a trigonometric ratio of the height of the falcon and the distance between the falcon and mouse B. The cosine of 72^(∘) will give us the desired ratio — remember that the cosine of an acute angle θ is the ratio between the lengths of the adjacent side and the hypotenuse. cos θ = Adjacent/Hypotenuse ⇒ cos 72^(∘) = 200/z Now we will solve this equation to find z.

cos 72^(∘) = 200/z
cos 72^(∘) (z) = 200
z = 200/cos 72^(∘)
z = 647.21359...
z ≈ 647.2

The approximate distance z between the falcon and mouse B is 647.2 feet.

b We will find the distance between the two mice y.
To do so, by writing the tangent of the given angles we will first find the horizontal distance between the falcon and mouse B, x+ y, and the horizontal distance between the falcon and mouse A, x. Let's start by finding x+ y by using the tangent of 72^(∘).

tan θ = Opposite/Adjacent
tan 72^(∘)= x+ y/200
â–¼
Solve for x+y
tan 72^(∘) (200) = x+y
615.53670... = x+y
615.5 ≈ x+y
x+y ≈ 615.5

The horizontal distance between the falcon and Mouse B is about 615.5 feet. Now we will find the horizontal distance between the falcon and mouse A by using the tangent of 62^(∘).

tan θ = Opposite/Adjacent
tan 62^(∘)= x/200
â–¼
Solve for x
tan 62^(∘) (200) = x
376.14529... = x
376.1 ≈ x
x ≈ 376.1

The horizontal distance between the falcon and mouse A is about 376.1 feet. From here we will find the distance between mouse A and mouse B.

Distance Between the Two Mice x+ y≈ 615.5 feet
Distance Between the Falcon and Mouse A x ≈ 376.1 feet
Distance Between the Two Mice y &= ( x+ y)- x &≈ 615.5- 376.1 &≈ 239.4 feet

The distance between mouse A and mouse B is about 239.4 feet.