Grade 12th PassMagical Mathematics[Interesting Approach]
If 8 sin2 A + 4 cos2 A = 5, THEN 4 sin2 A + 8 cos2 A is equal to?
If 8 sin2 A + 4 cos2 A = 5, THEN 4 sin2 A + 8 cos2 A is equal to?
1 Answer
vikas askiitian expert
sin2A = 1-cos2A ............1
8sin2A + 4cos2A = 5 ..........2 (given)
putting 1 in 2
8 - 8cos2 + 4cos2A = 5
cos2A = 3/4
sin2A = 1-cos2A = 1/4
so , value of 4sin2A+8cos2A = 4(1/4) + 8(3/4)
=7
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