1. 7.3 Finding Missing Parts Objectives: • Write trigonometric ratio’s
• Use trig to solve for a missing side
• Use trig to solve for a missing angle

2. Concept: Quick Review hypotenuse hypotenuse opposite opposite adjacent

3. Concept: Quick Review cont…
Find the sine, the cosine, and the tangent of theta
24.5
8.2
23.1
Shrink yourself down and stand where the angle is.
Now, figure out your ratios.

4. tan Concept: Finding Sides ) 20 m x 20 55
Ex: 1 Figure out which ratio to use. Find x Round to the nearest tenth.
20 m x
Now, figure out which trig ratio you have and set up the problem.
Shrink yourself down and stand where the angle is.
Cross multiply to solve for x.
tan 20 55 )

5. tan Concept: Finding Sides cont… ( ) = 80 ft x 80  72 )
2. Now, figure out which trig ratio you have and set up the problem.
Shrink yourself down and stand where the angle is.
3. Cross Multiply
4. Divide by tan (72)
tan 80  ( 72 ) ) =

6. Concept: Finding a Missing Angle Concept: Finding a Missing Angle
Steps to finding the missing angle of a right triangle using trigonometric ratios:
Draw the figure and mark on it HYP, OPP, ADJ relative to the unknown angle
OPP Ø
5.92 km
ADJ
2.67 km
HYP

7. Concept: Finding a Missing Angle Concept: Finding a Missing Angle
Steps to finding the missing angle of a right triangle using trigonometric ratios:
For the unknown angle choose the correct trig ratio which can be used to set up an equation
Set up the equation
OPP Ø
5.92 km
ADJ
2.67 km
HYP

8. Concept: Finding a Missing Angle Concept: Finding a Missing Angle
Steps to finding the missing angle of a right triangle using trigonometric ratios:
Solve the equation to find the unknown using the inverse of trigonometric ratio.
OPP Ø
5.92 km
ADJ
2.67 km
HYP
2nd cos ( ÷ ) ENT

9. Concept: Finding a Missing Angle
Your turn
Practice Together: Ø
3.1 km
2.1 km
Find, to one decimal place, the unknown angle in the triangle.
Ø = 34.1º

10. Concept: Finding a Missing Angle
Your turn
Practice Alone:
Find, to 1 decimal place, the unknown angle in the given triangle. Ø
9 m
4 m
Ø = 26.4º

11. Now go and practice. Remember, practice makes permanent!
Homework: PM 9.4 IXL-A2:Y.1
Now go and practice. Remember, practice makes permanent!