Solve.

[Jake13]

Im getting a bit confused with a few problems.


2cos2(x-3Pi/2)+5sin(x-Pi/2)=4


sin(90°-x)-2cos2x=-1
Some help?

[Six Pack]

So that's why I did so bad in math...there's so many letters I thought it was english.

Oh! but Pi = 3.14something

[The Girl From Ipanema]

Originally Posted by Jake13

Im getting a bit confused with a few problems.


2cos2(x-3Pi/2)+5sin(x-Pi/2)=4


sin(90°-x)-2cos2x=-1
Some help?

Let me try and work through this....it's been a loooooooong time since I've been in a math class....so I'll try and get back to you on this

EDIT: do you have to solve for x? or just simplify as best you can?

[Jake13]

Solve for x. -.-

[Dark Vamp]

Originally Posted by Jake13

Im getting a bit confused with a few problems.


2cos2(x-3Pi/2)+5sin(x-Pi/2)=4


sin(90°-x)-2cos2x=-1
Some help?

use a calculator

[The Girl From Ipanema]

2cos2(x-3Pi/2)+5sin(x-Pi/2)=4

this is one of those identity ones where you have to combine those like term thingies
personally i would substitute a letter like 'u' for the x-3Pi/2 and see if you can manipulate it from there to make it a bit simpler and then switch back to the trig function....

I know there's online math sites that can help you out with this kind of stuff.

sin(90°-x)-2cos2x=-1

substitute 1-sin2x for cos2x .....i assume the 2 symbolizes squared
sin (90 - x) - 2 (1-sinx) = -1
sin (90-x) - 2 + 2sin x = -1
sin (90-x) + 2sin x = +1 (took 2 from left side to right side)
i think right here you have to do some sort of substitution to simplify it in such a way that you can solve for a simpler variable and then switch it back to sin or cos to solve for x

I'm not really sure....I haven't done trig in years

[Six Pack]

Originally Posted by The Girl From Ipanema

2cos2(x-3Pi/2)+5sin(x-Pi/2)=4

this is one of those identity ones where you have to combine those like term thingies
personally i would substitute a letter like 'u' for the x-3Pi/2 and see if you can manipulate it from there to make it a bit simpler and then switch back to the trig function....

I know there's online math sites that can help you out with this kind of stuff.

sin(90°-x)-2cos2x=-1

substitute 1-sin2x for cos2x .....i assume the 2 symbolizes squared
sin (90 - x) - 2 (1-sinx) = -1
sin (90-x) - 2 + 2sin x = -1
sin (90-x) + 2sin x = +1 (took 2 from left side to right side)
i think right here you have to do some sort of substitution to simplify it in such a way that you can solve for a simpler variable and then switch it back to sin or cos to solve for x

I'm not really sure....I haven't done trig in years

What a show off.

[Jake13]

Thanks, that helped... A bit.

[Peace Frog]

It's playing with my head. I should be able to do it but at the moment I'm stumped. I would start with your sum and difference and double-angle formulas.

I see a pair of sum and difference substitutions in the first equation, that should make it a momentary mess, but you can simplify it down by solving what you know you can and then by plugging it back in to the equation.

I also see a double angle in the first part of your second equation. Make these substitutions and see what you can come up with.


No pun intended (this is not my website) but here are a listing of the trig formulas you should need. I was lucky enough to have my trig book as a makeshift mousepad when I read your question ^_^
http://hh4.hollandhall.org/kluitwiel...rreduction.htm


<stumped>

[**Muse*Cooze**]

2cos2(x-3Pi/2)+5sin(x-Pi/2)=4

so basically 3pi/2 = 270 degrees.
and pi/2 = 90 degrees.
and cos270 = 0.
and sin90= 1

2cos2x + 5sinx -5


i have no idea what to do after that.. haven't done trig in a month or so. you could do the common denominator.. of cosxsinx.