Question

help please! trig identities! use algebra to solve each equation over the domain of -2pi < x < 2 pi

a) 2sec^2x - 2 = 3 + tan x
b) 4sinxcosx=2 - 2cos^2x

Answer 1

So, you're saying you don't know a Pythagorean identity using secant and tangent?

Answer 2

i do it sec^2 + tan^2 = 1

Answer 3

you replace it

Answer 4

No, that's still incorrect, just like the last time.

\(\sin^{2}(x) + \cos^{2}(x) = 1\)

\(\tan^{2}(x) + 1 = \sec^{2}(x)\)

Answer 5

ok

Answer 6

Use that to get rid of the secant.

Answer 7

oh ok

Answer 8

ok what about b)?

Answer 9

How are your double angle formulas? Are they in your head?

Answer 10

i have a formula sheet

Answer 11

it's provided on the test as well

Answer 12

Divide the whole things by 2 then take a good, hard look at both sine and cosine double angle formulas.

Answer 13

can u work out a) for me please. i'm still not getting the right answers.. i thought it was tan x =3/2 and -2.. in radians or degrees but that doesn't seem like it

Answer 14

It would help if you would SHOW what you are doing.

4sinxcosx=2 - 2cos^2x

I suggested that you divide by 2. Did you do that?

Answer 15

a) 2x-3=0
x+2=0

b) how do u do sin2x=sin^2x

Answer 16

for a) i got the answers of .98, and 4.12 but couldn't get the -2 answer