Evaluate this expression

Evaluate

3(\sin x- \cos x)^4 + 6(\sin x + \cos x)^2+ 4 \sin^6x+4 \cos^6x

IIT JEE 1975

7 Answers

1
MATRIX ·

hmmmmmmmm........[12][12][12]...........

11
virang1 Jhaveri ·

3(sin2x + cos2x -2 cosxsinx)2 + 6(sin2x +cox2x + 2cosxsinx)+4 sin6+4cos6x

= 3(1-2cosxsinx)2+6(1+2cosxsinsx) + 4(sin6x + cos6x)

= 3(1 + 4 cos2xsin2x -4sinxcosx) +6 + 12cosxsinx + 4(sin6x + cos6x)

= 3 + 12 cos2xsin2x - 12sinxcosx + 6 + + 12cosxsinx +4(sin6x + cos6x)

= 9 +12cos2sin2x + 4(sin6x + cos6x)

(sin2x +cos2x)3 = sin6x + cos6x + 3cos2xsin2x(sin2x + cos2x)

9 +12cos2sin2x + 4 - 12cos2sin2x
= 13
Which is the final answer

1
MATRIX ·

[11][11][11].....[59]...........

11
virang1 Jhaveri ·

Bhaiyya is it rite?

11
Mani Pal Singh ·

21
tapanmast Vora ·

tum logo ne galat kiya hai........

rite METHOD :

LET sinx = 1
==> cosx = 0;

so 3+6+4 = 13 NOW ITS CRRCT [4] [4]

11
Mani Pal Singh ·

TAPAN
IIT WAS PURELY SUBJECTIVE IN 1975 [3][4]

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