McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Angles of Elevation and Depression
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Exercise 7 Page 665

Sketch a diagram describing the given situation. Then recall the definition of the inverse tangent.

≈14.8^(∘)

Practice makes perfect

We are asked to find the angle of depression at which a pilot should land if his altitude is 528 feet and his horizontal distance to land is 2000 feet. Let's sketch a diagram describing this situation. Let x represent the angle of depression.

To evaluate the value of x, we can use one of the inverse trigonometric ratios. Let's start with recalling 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 tanx. tan x=528/2000 Next we will recall that if ∠ A is an acute angle and the tangent of A is a, then the inverse tangent of a is the measure of ∠ A. Let's rewrite our equation. tan x=528/2000 ⇓ x=tan^(-1)528/2000 Finally, we will solve the equation using a calculator.
x=tan^(-1)528/2000
x=tan^(-1)0.264
x=14.788...
x≈ 14.8
The pilot should land at the angle of depression of approximately 14.8^(∘).