Question

sin A -cosA =0 so sin4A + cos4A =?
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Answer 1

Step-by-step explanation:

sinA - cosA =0

squaring both sides,

(sinA - cosA)^2 =0(^2)

using property of (a-b)^2,

sin^2A + cos^2A -2sinAcosA = 0

or sinA*cosA =1/2        as sin^2A + cos^2A=1

thus A = 45*  - sin 45 *cos 45 = 1/root2 * 1/root2

thus 4 A = 45*4 = 180*

sin 180* + cos 180* = 0.479(approx)