Find the value of \cos240°.

Mary Hammonds

Mary Hammonds

Answered question

2021-12-26

Find the value of cos240°.

Answer & Explanation

enhebrevz

enhebrevz

Beginner2021-12-27Added 25 answers

Reference angle for 240° is 60°: 240°=180°+60°
cos60°=12
As cos240°=cos60°, we have
cos240°=12
Rita Miller

Rita Miller

Beginner2021-12-28Added 28 answers

Write cos240° as cos(180°+60°)
Using the summation identity:
cos(180°)cos(60°)sin(180°)sin(60°)
Using trivial identity: cos180°=(1),cos60°=12,sin180°=0,sin60°=32
=(1)×120×32
=12
karton

karton

Expert2022-01-04Added 613 answers

The value of cos240° is 12

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