##### Like what you saw?

##### Create FREE Account and:

- Watch all FREE content in 21 subjects(388 videos for 23 hours)
- FREE advice on how to get better grades at school from an expert
- Attend and watch FREE live webinar on useful topics

# Evaluating Sine and Cosine at Other Special Angles - Problem 2

###### Norm Prokup

###### Norm Prokup

**Cornell University**

PhD. in Mathematics

Norm was 4th at the 2004 USA Weightlifting Nationals! He still trains and competes occasionally, despite his busy schedule.

In finding the sine and cosine of other special angles this problem asks me to find the cosine and sine of 11 Pi over 6. So I’ve drawn the angle 11 Pi over 6 it's just 3 degrees short of a full revolution. When you define the coordinates x and y of point p with the terminal side crosses the unit circle.

The method for this is first to identify the reference angle which is Pi over 6 and then calculate the sine and cosine of Pi over 6. Sine of Pi over 6 equals a 1/2 cosine of Pi over 6 is root 3 over 2. Then the sine and cosine of 11 Pi over 6 is going to be plus or minus these values, cosine of 11 Pi over 6 plus or minus root 3 over 2 I’ll feel it in later.

Sine 11 Pi over 6 plus or minus 1/2. Now look at what quadrant the terminal side lies in, it's in quarter to four and here the y values are negative. So the sine is going to be negative but the cosine will be positive and definition is a problem for us.

Cosine of 11 Pi over 6 is root 3 over 2 sine of 11 Pi over 6 is -1/2.

Please enter your name.

Are you sure you want to delete this comment?

###### Norm Prokup

PhD. in Mathematics, University of Rhode Island

B.S. in Mechanical Engineering, Cornell University

He uses really creative examples for explaining tough concepts and illustrates them perfectly on the whiteboard. It's impossible to get lost during his lessons.

Thiswas EXCELLENT! I am a math teacher and have been looking for an easy/logical way to explain the lateral area of a cone to my students and this was incredibly helpful, thank you very much!”

I just learned more In 3 minutes of polygons here than I do in 3 weeks in my math class”

Hahaha, his examples are the same problems of my math HW!”

###### Get Peer Support on User Forum

Peer helping is a great way to learn. Join your peers to ask & answer questions and share ideas.

##### Sample Problems (3)

Need help with a problem?

Watch expert teachers solve similar problems.

## Comments (0)

Please Sign in or Sign up to add your comment.

## ·

Delete