right triangle trigonometry advanced math 6.2. 2 right triangle 0 < < 90 six trig ratios ...
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Right Triangle TrigonometryRight Triangle Trigonometry
Advanced Math 6.2
Advanced Math 6.2 2
Right triangle• 0 < q < 90• Six trig ratios
q
Side adjacent to q
Sid
e o
pposi
te t
o q
hypotenuse
sinopp
hyp
sine
cosadj
hyp
cosine
tanopp
adj
tangent
cschyp
opp
cosecant
sechyp
adj
secant
cotadj
opp
cotangent
Advanced Math 6.2 3
Example• Find the 6 trig
functions of the triangle
q
5
12
13
sin
cos
tan
csc
sec
cot
12
13
5
13
12
5
13
12
13
5
5
12
Advanced Math 6.2 4
If given the angle• Make a triangle• Make the short side 1• Two common triangles
• 45°- 45°- 90°• 30°- 60°- 90°
Advanced Math 6.2 5
45°- 45°- 90° triangle• From geometry
– The two sides opposite equal angles are equal lengths
45°
45°
1
1
• From Pythagorean thrm.– hyp is
2
2
• Find sin, cos, and tan of 45°
Advanced Math 6.2 6
30°- 60°- 90° triangle• Half of an equilateral
triangle
60°
1
2
• From Pythagorean thrm.– opp is
2
3
• Find sin, cos, and tan of 30° and 60°
30°
1
3
Advanced Math 6.2 7
Cofunctions• sin and cos• tan and cot• sec and csc
• Cofunctions of complementary angles are =
2sec30
3
csc60
2
3
Advanced Math 6.2 8
You try• Find sin, cos, and tan of p/3
radians.
Advanced Math 6.2 9
Special angles• Chart on page 462
Advanced Math 6.2 10
TRIG IDENTITIES
1sin
csc
1csc
sin
1
seccos
1cos
sec
1cot
tan
1tan
cot
Reciprocal Identities
sintan
cos
Quotient Identities
coscot
sin
2 21 cot csc
Note
2 21 tan sec
2 2sin cos 1 Pythagorean Identities
22sin sin
sin sin
Advanced Math 6.2 11
SOH CAH TOA
so
h
SOH
ca
h
CAH
to
a
TOA
Advanced Math 6.2 12
Examples• If tan q = 5, find
• cot q• cos q• tan (90° - q)• csc q
Advanced Math 6.2 13
Examples• Use trig identities to show that
cos sec 1
21 sin 1 sin cos
2tan cotcsc
tan
Advanced Math 6.2 14
Using the calculator for trig functions
• Check the mode• Only buttons for sin, cos, and tan
• May need reciprocal identities
Advanced Math 6.2 15
Examples• Evaluate the following using a
calculator. Round to three decimal places.
• sin 16.35°• csc 16.35°• sec 0.75• cos 0.75
Advanced Math 6.2 16
Solving right triangles
60°
18y
Solve for y.
45°
r
20
Solve for r.
Advanced Math 6.2 17
Angles of elevation and depression
observer
observer
object
object
angle of elevation
angle of depression
Advanced Math 6.2 18
Example• A 10´ ladder leans against the side
of a house. The ladder makes an angle of 60° with the ground. How far up the side of the house does the ladder reach?
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