Math Is Fun Forum

djbip

Member

Registered: 2008-03-27

Posts: 13

A few other trig questions

sinθ=cosθ 

sinθ-2cosθ=0

secθ=4secθ 

period 0 ≤ x ≤ 360°

I'm sorry, i know this is easy, but i don't seem to get it
Thanks!

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: A few other trig questions

sin = cos when angle where y = x line
intersects a circle.
That's at 45 and 180 + 45 (or 225 degrees)
sin is like y over hypot.
cos is like x over hypot.
if hypot is 1, then forget about hypot.
x/1 == x, n'est-ce pas?

Last edited by John E. Franklin (2008-05-25 14:17:10)

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igloo myrtilles fourmis

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: A few other trig questions

#2.) sin = 2 cos where y = 2x on the unit circle of trig class.
Whatever angle corresponds to going right 1 unit and up 2 units is the answer.
Also add 180 degrees for the other answer.
Do you know inverse tangent.  Use that for sure.
It undoes any slope into an angle.
Should be between 61 and 75 degrees.  I don't have it memorized.

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igloo myrtilles fourmis

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: A few other trig questions

#3.) I'm not going to touch the secant one because I am afraid of infinity.

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igloo myrtilles fourmis