Question

if tanx = 1 , then find ,
8sin x + 5 cosx by
sin^3x-2 cos^3x+7cosx
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Answer 1

sec X = √1+ tan2 X

= √1 + 1

= √2

cos X = 1 / √2

sin X = √(1 - cos2 X)

= √1 - (1 / √2)2 = 1 / √2

Now, (8 sin X + 5 sin X) / (sin3 - 2 cos3 + 7 cos X)

[8 x 1 / √2 + 5 x 1 / √2 / (1 / √2)3 - 2 x (1 / √2)3 + 7 x 1 / √2

= [(8 + 5) / √2] / [1 / 2√2 - 2 / 2√2 + 7 / √2]

= [(8 + 5) / √2] / [(1 - 2 + 14) / 2[(8 + 5) / √2]

= (13 x 2) / 13 = 2

• HOPE THIS HELPS YOU •