7-2 Right Triangle Trigonometry

Pull out those calculators!!!

What? Did I read that right?

Yes – we will be using calculators now. You may use either a graphing calculator or scientific calculator. The only thing is that you must make sure you know how to use the calculator. If you don’t, see me TODAY!!

Don’t get too excited. You have to know how to put it into the calculator after correctly interpreting the information.

Absolutes1. Make sure the calculator is in degrees Scientific: Press DRG button till you see

DEG on the face Graphing: Mode then toggle down and

toggle left/right to degrees

2. Make sure you know how to find sin/cos/tan of angles

Scientific: put in number, then press function

Graphing: Function, number, enter

Absolutes

3. If you have a sine or cosine value and want to find the angle, you will use sin-1 or cos-1. These are the inverse functions.

Remember the definition of inverse: Put in the answer, get out the original (angle)

Everything will be based on the triangle shown below. As it is called “Right Triangle Trig” you can assume there is a right angle. We will always have the right angle in the same place.

A

B

C

a

b

c

Note: B = 42 means angle B = 42.

Examples

ΔABC is a right triangle with C = 90. Solve for the indicated part(s).

1. A = 42, b = 4; c = ?

2. b = 4, c = 7; B = ?

Word Problems sorry Monica

Before we do this, you need to understand 2 standard phrases:

Angle of Elevation: Angle rising from horizontal

Angle of Depression: Angle dropping from horizontal

Examples

3. How tall is a tree whose shadow is 47 feet long when the angle of elevation is 49.3

4. One of the equal sides of an isosceles triangle is 23 cm and the vertex angle is 43. How long is the base?

Examples

5. A balloon is floating between 2 people who are 50 feet apart. The angle of elevation of balloon is 63.5 from person A and 32.6 from person B. How high up in the air is the balloon?