Solving for Sides
September 30, 2013
What's Going On?
sin, cos or tan?
Solving for sides.
Side wars!
Learning Goal ­ I will use sin, cos and tan to solve for side lengths in right triangles.
1
Solving for Sides
September 30, 2013
F.F.M.
Name: _________
Date:_______
Explain, in words, what the letters in
sohcahtoa stand for and what it helps us
remember.
Use full sentences, you don't need to write
this question.
sohcahtoa helps us remember what sin, cos and tan of an angle are.
sin of an angle is the length of the opposite side, divided by the length of the hypotenuse
cos of an angle is the length of the adjacent side, divided by the length of the hypotenuse
tan of an angle is the length of the opposite side, divided by the length of the adjacent side
2
Solving for Sides
It's amazing!
September 30, 2013
YES!!!!
sohcahtoa
Y
O
LO U
V
E
I
T
!
3
Solving for Sides
September 30, 2013
The Ratios
B
c
A
b
a
C
4
Solving for Sides
September 30, 2013
sin, cos or tan?
We can use sin, cos and tan to determine the lengths of sides in right triangles.
Before we can do anything else, we need to decide which one we are going to use!!
How can we do that?
5
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side a to one decimal place.
B
16.0 cm
24o
C
A
6
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side C
B
57o
C
9.5 cm
A
1. Identify the reference angle.
2. Determine our "sides of interest" ­ what side(s) we have (opposite, adjacent, hypotenuse)
­ what side we want (opposite, adjacent, hypotenuse)
3. Our sides of interest tell us which trig ratio to use.
­ opposite and hypotenuse ­ adjacent and hypotenuse
­ opposite and adjacent
7
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side b to one decimal place.
B
21.0 cm
31o
C
A
8
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side c to one decimal place.
B
7.1 cm
40o
C
A
9
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side b to one decimal place.
B
9.0 cm
28o
C
A
10
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side a to one decimal place.
B
19o
C
44.5 cm
A
11
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side c to one decimal place.
B
20o
C
12.5 cm
A
12
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side a to one decimal place.
B
55o
C
17.2 cm
A
13
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side a to one decimal place.
B
61o
C
14.3 cm
A
14
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side c to one decimal place.
B
70o
C
31.3 cm
A
15
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side b to one decimal place.
B
72o
C
81.3 cm
A
16
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side c to one decimal place.
B
62o
3.9 cm
C
A
17
Solving for Sides
September 30, 2013
sin, cos or tan?
Determine the length of side b to one decimal place.
B
65o
11.1 cm
C
A
18
Solving for Sides
September 30, 2013
Solving for Sides
To solve for a side in a right triangle:
1. Decide if you are going to use sin, cos or tan.
2. Set up your trig ratio using sin, cos or tan.
3. Plug in your values.
4. Evaluate your trig ratio to 4 decimal places.
5. Cross multiply.
19
Solving for Sides
September 30, 2013
Solving for Sides
Determine the length of side a to one decimal place.
B
16.0 cm
24o
C
A
20
Solving for Sides
September 30, 2013
Side Wars
Find the length of side ___.
21