Question

Can someone help me solve this?

cos(x^2+45)+tan(4x+90) = sin(3x+120)

A step by step would be great.

Answer 1

by solving do you mean proving?

Answer 2

Yes. :)

Answer 3

What methods have been discussed?

Answer 4

We are solving for x not proving this. This isn't an identity.

Answer 5

Or does it say to disprove or prove?

Answer 6

Ah yes, my bad. It says solve.

Answer 7

Can you tell me what methods in class have been discussed?

Answer 8

None, this is from a book with only problems I picked up at barnes and noble. We haven't done this and wont do it for another year or two. I've had no problems with the book up to this point.

Answer 9

can you tell me what methods the book has discussed?

Answer 10

None. It's a book of only problems. It starts from Geometry and works it's way up in problems.

Answer 11

Name of book please

Answer 12

Math Review for the High School Classroom

Answer 13

I looked for it online and can't find it.

Answer 14

I didn't see the book. :(
So there are no examples?

Answer 15

No examples, just questions. :c How did you learn it?

Answer 16

Honestly, I don't know without seeing some example or them mentioning some method they want to use.

Answer 17

Ah, okay. Thanks, anyway. :)

Answer 18

cos(x^2+45)+tan(4x+90) = sin(3x+120)

cos(x^2+45)+sin/cos(4x+90) = sin(3x+120)
dividing everything by sin.
tan(x^2+45) + sec(4x+90) = 3x + 120
i don't remember trig that well, but you can convert it to this i think.

Answer 19

You can't do that...
Like you can't divide by the trig part
The trig part is a function not a number or variable on its own

Answer 20

oh

Answer 21

Are the angles in radians or degrees?

Answer 22

I'll assume degrees for now.

Answer 23

Degrees, yeah. ^^

Answer 24

45,90,120 suggest they are in degrees...

we can convert sin and cos in tan,
like cos A = tan (sqrt (1-A^2)/A)
something like this

and then use tan A+tan B formula......
but if thats possible, the algebra is going to be very ugly....

Answer 25

but @hartnn tan(90) does not exist
you were talking about the sum identity for tan right?

Answer 26

@myininaya tan(a+90) = -1/tan(a), since they're perpendicular.

Answer 27

not tan(A+B)
tan A +tan B , where B = 4x+90
and yeah, tan (A+90) = - cot 90
so maybe convert cos into cot and use cotA-cotB formula...
i don't think that will be of any use though....