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how the eff do i teach myself trig in an hour

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melanie.dee:
:( i find myself just leaving these stupid questions entirely blank the whole time. i just do NOT get trig equations. like solving them with exact values and the unit circle and all that shit.

how do i teach myself this is an hour or less haha? anyone have any really simple explanations. i mean questions like

Find the exact solutions of cos(3xpi) = -sin(3xpi) for 0 < or equal to x < or equal to 1

and..

Solve the equation root(3)sin(2x) + cos(2x) = 0 for x is an element of [0,2pi], giving exact values in terms of pi.

I can normally work out how to get to part where i have something equal one of the things from the exact values thing, but then i dont know how many solutions i need and how to work them out or ANY of that shit.

hifer:

--- Quote from: "melanie.dee" ---:( i find myself just leaving these stupid questions entirely blank the whole time. i just do NOT get trig equations. like solving them with exact values and the unit circle and all that shit.

how do i teach myself this is an hour or less haha? anyone have any really simple explanations. i mean questions like

Find the exact solutions of cos(3xpi) = -sin(3xpi) for 0 < or equal to x < or equal to 1

and..

Solve the equation root(3)sin(2x) + cos(2x) = 0 for x is an element of [0,2pi], giving exact values in terms of pi.

I can normally work out how to get to part where i have something equal one of the things from the exact values thing, but then i dont know how many solutions i need and how to work them out or ANY of that shit.
--- End quote ---


In this type of questions, what u have to do is basically express the eqn using 1 trig function, eg for 1st qs:

cos(3xpi) = -sin(3xpi)   <- Divide both sides by cos(3xpi)
1 = -tan(3xpi)
tan(3xpi) = -1
Reference angle is pie/4 and angle is in 2nd and 4th quadrant
then proceed to solve for all solns in defined domain..

kido_1:
These questions are easy...once you get the trick:

 1)sinx = cosx     is the same as (dividing both sides by cosx)
 tanx = 1

2) sin2x-cos2x=0
sin2x=cos2x
tan2x=1

3) cos100pix= sin100pix
tan100pix = 1

It gets boring after a while...
See if you can do your questions now. Just divide both sides by cos(angle).

melanie.dee:
no no see thats the part i CAN do. i can transpose it and convert it to tan or whatever find. but i dont get how the whole reference angles thing works and quadrants and how to change the domain. actually i just did a prac question with the solutions next to me and that kinda helped i think i getit, but then normally i look at these questions and go wtf. actualy dw i dont think its anything i can get help with here haha. i think i need someone to explain to me in person. or ill try work it out haha.

Fitness:

--- Quote from: "melanie.dee" ---how do i teach myself this is an hour or less haha? anyone have any really simple explanations. i mean questions like
--- End quote ---


If you have some clue but forgot how and need to refresh your memory fast, the i suggest you try the reference note pads from the itute website.

Edit: Just realised that there is no specific trig notepad ... However some could be contained within others and these are still good for the other topics. Certainly got me on the right track with probability.

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