Trig question

  • Thread starter Miike012
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  • #1
Miike012
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Homework Statement


If A= 30 deg.. verify that..
Sin2A = 2SinACosA
First off..On the left side where it says 2A... does that mean multiply 30deg by two? and on the right side does the two also mean multiply?

Anyways... since it is asking me to verify that they are equal... am i basically using the trig identities to prove that this statment is true by only working with one side and trying to make is look like the other side.?


Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
phyzguy
Science Advisor
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Since this is a trig identity that is always true, I don't think they want you to use trig identities to show it. I think they just want you to calculate
sin(60 degrees) on the left hand side and 2*sin(30degrees)*cos(30degrees) on the right hand side and verify that they are equal.
 
  • #3
Miike012
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Alright... So I was correct when they said multiply two by the deg on the left side? This is all new to me.... So how would you calculate that they are equivalent?
 
  • #4
eumyang
Homework Helper
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It's quite simple. Evaluate sin 60°, sin 30°, and cos° 30 (using the knowledge of the 30°-60°-90° triangle) and plug into sin 60° = 2 sin 30° cos 30° to verify.
 

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