Question

3(sin2x+cos2x)+3(3−sin2x−cos2x)=28 show that either cos x = 0 or tan x = –1

Answer 1

the question you have typed has an obvious mistake

Answer 2

it has no solution

Answer 3

expand the LHS and it all cancels to 9

so 9=28

a false statement , no solution

Answer 4

it's solvable. put 3-sin2x-cos2x=1-cos2x-sin2x=2. This on expansion gives us an equation in sin^2 x and cos^2 x, divide by cos^2 x and simplify to get the answer. It's tan x= -1.

Answer 5

k well I still dont understand what you did/are talking bout.

but if you are correct, note that the answer the original asker gave said cosx =0 or tanx=-1

you divided out cos^2x , which is a variable , and u cnt divide by a variable