Teacher Instructions
1.
2.
3.
4.
5.
Copy and cut out cards from last page so that each student gets
measurements to draw a triangle.
Hand out worksheet, card, protractor and graph paper to each
student. I had my students work in pairs, but they still had different
triangle lengths so they had different answers.
Have students complete #1-10 with their partner, comparing answers
as they go.
Discuss with class their findings and make sure everyone filled in the
chart for #10 correctly.
I then worked out practice problems with students.
Exploring SOH CAH TOA
Draw a triangle on the CENTER of your grid paper using
the dimensions on your card. Be sure to draw the picture
like the following. (You will do this for three different
triangles.)
C
B
x
A
1. Find the length of the hypotenuse and label on your picture. (HINT: Use
Pythagorean Theorem)
2. Using your protractor, measure angle x and label inside the triangle. Be as
accurate as possible!
3. Fill in the table of ratios of lengths of the sides of the triangle:
B
A
B
C
A
C
Fraction Form
Decimal Form
4. Now look at your calculator. Change the mode to degree by pressing MODE and
selecting DEGREE.
5. Look above the numbers. There are buttons labeled SIN, COS, and TAN. We are
about use those! Yeah!
6. Now look at your calculator. Change
the mode to degree by pressing
MODE and selecting DEGREE.
7. Look above the numbers. There are
buttons labeled SIN, COS, and TAN.
We are about use those! Yeah!
8. Fill in the table for angle x. Write
answer as a decimal. For example,
if you wanted to find sin (30), you
would type SIN, 30, ENTER in your
calculator!
sin(x)
cos(x)
sin(x)
cos(x)
tan(x)
tan(x)
9. Now, match up the side ratios from the first chart with the corresponding trig
expression (sin, cos, or tan).
sin(x) = ____________ cos(x) = ________________ tan(x) = ________________
10. Compare with your partner. Did you guys get the same matches? If not,
someone made a mistake someone! Please fix it!
Opposite
(B)
Hypotenuse
(C)
Adjacent
(A)
Let’s practice some problems!
Find tan A and tan B. Write each answer as a decimal rounded to four decimal places.
1.
2.
tan A________
tan A ________
tan B ________
tan B ________
Find the sine and cosine ratios.
3.
sin z  =______
cos z  =______
82
18
80
4.
18
82
80
sin x  =______
cos x  =________
Find the value of x to the nearest tenth.
5. x = __________
6. x = _______
Use a sine or cosine ratio to find the value of each variable.
7.
.
26
8.
30
x
18
y
x
y
32
x = ___________
x = ___________
y = ___________
y = ___________