Pre-Algebra Chapter 9
Pre-Algebra Chapter 9
Pre-Algebra Chapter 9
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A Follow-Up of Lesson 9-8<br />
Finding Angles of a Right Triangle<br />
A calculator can be used to find the measure of an acute angle of a right triangle if<br />
you know the measures of two sides of the triangle.<br />
Example<br />
The end of an exit ramp from an interstate highway is 22 feet higher than the<br />
highway. If the ramp is 630 feet long, what angle does it make with the highway?<br />
630 ft<br />
22 ft<br />
x˚<br />
A<br />
Determine which trigonometric ratio is needed to solve the problem. Since<br />
you know the measure of the leg opposite A and the hypotenuse, use the<br />
sine ratio.<br />
Write the ratio.<br />
opposite<br />
sin A Sine Ratio<br />
hy potenuse<br />
22<br />
sin A <br />
Substitution<br />
6 30<br />
Use a calculator to find the measure of A. The SIN 1 function will find the<br />
angle measure, given the value of its sine.<br />
2nd SIN 22 630 ENTER 2.001211869<br />
To the nearest degree, the measure of A is 2°.<br />
Exercises<br />
Use a calculator to find the measure of each acute angle. Round to the nearest degree.<br />
1. 2.<br />
7 ft<br />
A<br />
B<br />
13.5 ft<br />
C<br />
E<br />
17 m<br />
D<br />
39 m<br />
F<br />
3. A flower garden is located 46 meters due west of an elm tree. A fountain is located<br />
19 meters due south of the same elm tree. What are the measures of the angles<br />
formed by these three park features?<br />
www.pre-alg.com/other_calculator_keystrokes<br />
482 Investigating Slope-Intercept Form<br />
482 <strong>Chapter</strong> 9 Real Numbers and Right Triangles
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