Daisy R.

# How do i simplify this?

Hi my problem is the following.

Use the sum and difference identity to find the exact value of sine cosine and tangent.
195°=60°+135°

And here is what i did
Sin(195)=sin(60+135)
=sin60cos135+cos60sin135

But i dont know how to simplify that result

I did the samething with cos
Cos(195)=cos(60+135)
=cos60cos135-sin60sin135

And i have the same problem i dont get how to simplify that?
Can someone help please and how do it for tangent?

Thank you:)

## 3 Answers By Expert Tutors

By:

Tutor
5 (3)

Tutoring in Precalculus, Trig, and Differential Calculus

Arthur D.

tutor
Daisy, use your graphing calculator to find sin(60), sin(135), cos(60), cos(135), tan(60),
and tan(135), or go on the web. There are many sites that will give you these values.
You can also find sin(195), cos(195), and tan(195) to get the correct answers in order to check your work after using the Addition and Subtraction Identities.
Report

01/31/14

Tutor
4.8 (4)

Mathematics professor at Community Colleges

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