Download Trigonometric Ratios in the Calculator: Find sin 35° Find <A to the

UNIT 11: INTRO TO TRIG PART 1
Let's start with a quick review of the three trigonometric functions we already
understand. Remember that these functions work only in right triangles.
where A represents the angle of reference.




These formulas ONLY work in a right triangle.
The hypotenuse is always across from the right angle.
Check the question for how to round your answer.
You will need a scientific or graphing calculator.
Trigonometric Ratios in the Calculator:
Find sin 35°
Find <A to the nearest degree,
Set MODE to Degree
given cos A = 3/5
Type entry on the Home Screen
Set MODE to Degree
Type entry on the Home Screen.
Hit 2nd cos to get the cos-1
Degrees, Minutes, and Seconds (DMS): Angles are measured in
degrees, minutes, and seconds.
Degrees

Degrees-Minutes-Seconds
Where do you find all the degree, minute, and second buttons in the calculator?
Standard Position:
An angle is in standard position if its vertex is located at
the origin and one ray is on the positive x-axis.
 The ray on the x-axis is called the initial side and the other ray is called the
terminal side.
 If the terminal side of an angle lies "on" the axes (such as 0º, 90º, 180º, 270º,
360º ), it is called a quadrantal angle.
 The angle shown below is referred to as a Quadrant II angle since its terminal
side lies in Quadrant II.

The angle is measured by the amount of rotation from the initial side to the
terminal side.
 If measured in a counterclockwise direction the measurement is positive.
 If measured in a clockwise direction the measurement is negative.

If two angles in standard position have the same terminal side, they are called
coterminal angles. (add or subtract 360o)
Angle of Elevation: line of sight is titled upward
angle of
elevation
forms a right
angle
horizontal line
Angle of Depression: line of sight is titled downward
horizontal line
angle of
depression
forms a right
angle
horizontal line
**angle of elevation = angle of depression**
TRIGONOMETRY RADICALS IN THE FIRST QUADRANT
30
sin 
cos 
tan 
45
1
2
3
2
3
3
60
2
2
2
2
3
2
1
2
1
3
 REFERENCE ANGLE – the positive acute angle formed from the terminal side
of an angle and the x-axis. (quickest angle back to the x-axis!)
 ASTC – shows you where the trig functions (sine, cosine, tangent) are positive
or negative.
 UNIT CIRCLE – a circle with a radius of 1
( x, y )  cos  , sin  
cos   x
sin   y
y sin 
tan   
x cos 