1. Day 2: Primary Trigonometric Ratios
Unit 8: Trigonometry

2. Learning Goals
To be able to use the primary trigonometric ratios

3. Labeling a Triangle
Vertices/angles are ALWAYS denoted with a capital letter
Sides are ALWAYS denoted with a lower case letter
The side and angle that are across from each other are ALWAYS the same letter

4. Labeling a Triangle

5. Primary Trig Ratios Activity
You need a ruler and a protractor
You may work in partners
You have 15 minutes

6. Primary Trig Ratios 𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 ℎ𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 = sin 𝑥
𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 ℎ𝑦𝑝𝑜𝑡𝑒𝑛𝑢𝑠𝑒 = cos 𝑥
𝑜𝑝𝑝𝑜𝑠𝑖𝑡𝑒 𝑎𝑑𝑗𝑎𝑐𝑒𝑛𝑡 = tan 𝑥

7. SOHCAHTOA

8. Evaluate. c) tan 15° a) sin 60° =0.8660 b) cos 45° =0.7071 =0.2679
What do these values represent?
The ratio of the two sides
NOT the value of any one side
NOT the value of the angle
b) cos 45°
=0.7071
c) tan 15°
=0.2679

9. Evaluate. a) sin 𝐴 =0.5 𝐴= sin −1 0.5 𝐴=30°
What do these values represent?
The values of angles A, B and C
b) cos 𝐵 = 3 10
𝐵= cos −
𝐵=73°
c) tan 𝐶 =1.4239
𝐶= tan −
𝐶=55°

10. List the primary trig ratios for angle A.
sin 𝐴 = 4 𝑐 cos 𝐴 = 6 𝑐 tan 𝐴 = 4 6
hypotenuse
opposite A
adjacent

11. List the primary trig ratios for angle B.
sin 𝐵 = 6 𝑐 cos 𝐵 = 4 𝑐 tan 𝐵 = 6 4 B
hypotenuse
adjacent
opposite

12. Success Criteria
I CAN properly label a right triangle and set up the primary trigonometric ratios

13. To Do…
Worksheet
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