Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
4. The Tangent Ratio
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Exercise 25 Page 492

Practice makes perfect
a We are given that the photographer is positioned 14 feet away from the center of the class and he turns 50^(∘) to look at either end of class. Let's make a sketch of this situation. Let x represents the distance between the center and the end of the class.

Notice that we can use one of the trigonometric ratios to evaluate the value of x. Let's recall that the tangent of ∠ A is the ratio of the leg opposite ∠ A to the leg adjacent ∠ A. Using this definition, we can create an equation for tan 50^(∘). tan 50^(∘)=x/14 Let's solve the above equation.

tan 50^(∘)=x/14
14*tan 50^(∘)=x
x=14*tan 50^(∘)
x=16.6845...
x≈ 16.7

The value of x is approximately 16.7 feet. To find the distance between the ends of the class we should multiply x by two. 16.7* 2=33.4 The distance between the ends of the class is approximately 33.4 feet. Notice that this value is only an approximation, as we used approximate values to evaluate it.

b In this part we are given that the photographer turns another 10^(∘) either way to set the camera range. Let y be the new distance from the center to the end of the class.

To find the value of y we can use one of the trigonometric ratios. Again recall that the tangent of ∠ A is the ratio of the leg opposite ∠ A to the leg adjacent ∠ A. Using this definition, we can create an equation for tan (50^(∘)+10^(∘)). tan (50^(∘)+10^(∘))=y/14Let's solve the above equation.

tan (50^(∘)+10^(∘))=y/14
tan 60^(∘)=y/14
14*tan 60^(∘)=y
y=14*tan 60^(∘)
y=24.2487...
y≈ 24.2

The value of y is approximately 24.2 feet. Let's add this information to our diagram.

Now we will evaluate the difference of the distances between the center and the end of the class. To do this we will subtract 16.7 from 24.2. 24.2- 16.7=7.5 Since we are given that each student needs 2 feet of space we will divide 7.5 by 2 and round the result to the nearest integer that is not greater than this number. 7.5/2=3.75≈ 3 After increasing the angle, approximately 3 more students can fit at the end of each row.