Download Section 9.5:

Section 9.5:
Trigonometric Ratios
trigonometric ratio – a ratio of the lengths
of two sides of a right triangle.
The three basic trigonometric ratios are
sine, cosine, and tangent.
B
hypotenuse
c
side opp.
a
A
C
A
b
side adjacent
to
A
Trigonometric Ratios
sin A = side opposite A = a
hypotenuse
c
cos A = side adjacent A = b
hypotenuse
c
tan A = side opposite
side adjacent
A = a
A
b
Example 1:
Use a calculator to approximate the given
value to four decimal places.
a) cos 13°
≈ 0.9744
b) sin 27°
≈ 0.4540
c) tan 66°
≈ 2.2460
Example 2:
Find the sine, cosine, and tangent of angle D.
E
14
F
50
48
D
Example 3:
Find the value of each variable. Round
decimals to the nearest tenth.
t
34
23°
s
HOMEWORK (Day 1)
pg. 562 – 563; 10 – 32 even
angle of elevation – the angle that your line
of sight makes with a line drawn
horizontally.
Example 4:
You are measuring the height of a building.
You stand 100 feet from the base of the
building. You measure the angle of
elevation from a point on the ground to the
top of the building to be 48°. Estimate the
height of the building.
About 111 ft
Example 5:
A driveway rises 12 feet over a distance d at
an angle of 3.5°. Estimate the length of the
driveway.
About 197 ft
HOMEWORK (Day 2)
pg. 563; 34 – 39