Question Number 11456 by Joel576 last updated on 26/Mar/17

sin x − cos x = a, (π/4) ≤ x ≤ (π/2) Which statement is correct? (1) sin^2 x − cos^2 x = −(1/2)(√(3 + 2a^2 − a^4 )) (2) sin^4 x + cos^4 x = (1/8)(−3a^4 + 6a^2 + 5) (3) sin 2x = ((1 − a^2 )/2) (4) tan^2 x + cot^2 x = ((−3a^4 − 2a^2 + 8a + 13 )/(2(a^4 + 2a^2 + 1)))

Commented byajfour last updated on 26/Mar/17

none seem to be correct..

Commented byJoel576 last updated on 26/Mar/17

why?

Commented byJoel576 last updated on 26/Mar/17

sorry, in statement (4) it must be tan^2 x + cot^2 x

Answered by ridwan balatif last updated on 26/Mar/17

Answered by ridwan balatif last updated on 26/Mar/17

Commented byJoel576 last updated on 27/Mar/17

thank you very much