GEOMETRY HELP Use the triangle to find sin T, cos T, sin G, and cos G. Write your answer in simplest...
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Transcript of GEOMETRY HELP Use the triangle to find sin T, cos T, sin G, and cos G. Write your answer in simplest...
GEOMETRYHELP
Use the triangle to find sin T, cos T, sin G, and cos G. Write your answer in simplest terms.
sin T = =1220
35=
oppositehypotenuse
cos T = =1620
45=
adjacenthypotenuse
sin G = =1620
45=
opposite hypotenuse
cos G = =1220
35=
adjacent hypotenuse
Quick Check
Sine and Cosine RatiosLESSON 8-4
Additional Examples
GEOMETRYHELP
A 20-ft. wire supporting a flagpole forms a 35˚ angle with the
flagpole. To the nearest foot, how high is the flagpole? The flagpole, wire, and ground form a right triangle with the wire as the hypotenuse.
Because you know an angle and the measures of its adjacent side and the hypotenuse, you can use the cosine ratio to find the height of the flagpole.
cos 35° =height
20 Use the cosine ratio.
height = 20 • cos 35° Solve for height.
The flagpole is about 16 ft tall.
Sine and Cosine RatiosLESSON 8-4
Additional Examples
Quick Check
20 35 Use a calculator.
GEOMETRYHELP
A right triangle has a leg 1.5 units long and hypotenuse 4.0
units long. Find the measures of its acute angles to the nearest degree.
Draw a diagram using the information given.
Use the inverse of the cosine function to find m A.
cos A =1.54.0 0.375= Use the cosine ratio.
Use the inverse of the cosine.m A = cos–1(0.375)
Round to the nearest degree.m A 68
Sine and Cosine RatiosLESSON 8-4
Additional Examples
Use a calculator.0.375
GEOMETRYHELP
(continued)
To find m B, use the fact that the acute angles of a right triangle are complementary.
The acute angles, rounded to the nearest degree, measure 68 and 22.
m A + m B = 90 Definition of complementary angles
Substitute.68 + m B 90
m B 22
Sine and Cosine RatiosLESSON 8-4
Additional Examples
Quick Check