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Edutopia
 3 years ago
question about the proof of trig addition formulas for cos:
Edutopia
 3 years ago
question about the proof of trig addition formulas for cos:

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Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0sorry about the scrolling: http://en.wikipedia.org/wiki/Proofs_of_trigonometric_identities on the part with the diagram for trig addition formulas, where does "RPQ = (PI/2)  RPQ" come from?

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0also any sites with a better, easy to understand, definition would be greatly appriciated

AccessDenied
 3 years ago
Best ResponseYou've already chosen the best response.1RPQ = pi/2  RQP pi/2 radians is 90 degrees. RPQ = 90 degrees  RQP which we can see because that triangle is a right triangle, so the other two angles have to be complementary to add up to 180 degrees interior.

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0but PRQ is only one of the complementary angles, how do i know that it is half of 90?

AccessDenied
 3 years ago
Best ResponseYou've already chosen the best response.1I believe PRQ is meant to be a right angle, 90 degrees or pi/2 radians, although it doesn't appear to be indicated as such...

AccessDenied
 3 years ago
Best ResponseYou've already chosen the best response.1dw:1357875756276:dw Just drawing diagram here

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0im sorry we got it switched around somewhere its RPQ not PQR

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0they are proving that RPQ=alpha

AccessDenied
 3 years ago
Best ResponseYou've already chosen the best response.1Since PRQ is a right triangle with right angle PRQ, RPQ and RQP are complementary. <RPQ + <RQP + <PRQ = 180 <RPQ + <RQP + 90 = 180 <RPQ + <RQP = 90 <RPQ = 90  <RQP Would that make sense?

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0OH RPQ is a TRIANGLE! oops

AccessDenied
 3 years ago
Best ResponseYou've already chosen the best response.1the pi/2 is just radians, i was using degrees. sorry if that is confusing...

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0no its not i understand radians

Edutopia
 3 years ago
Best ResponseYou've already chosen the best response.0aha i see it, thank you very much!

AccessDenied
 3 years ago
Best ResponseYou've already chosen the best response.1You're welcome! :)
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