If sinA=3/4 then the value of sin3A
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Answer:
9/16
Step-by-step explanation:
sin3A= sin(A+2A)
= sinA.cos2A+cosA.sin2A
= sinA(2cos^2A-1)+cosA.2sinA.cosA
=2sinAcos^2A-sinA+2sinA.cos^2A
=4sinAcos^2A-sinA
=4sinA.(1-sin^2A)-sinA
=4sinA-4sin^3A-sinA
=3sinA-4sin^3A { you can see this is identify too}
sin3A=3sinA-4sin^3A
=3(3/4)-4(3/4)^3
=9/4-108/64
=9/16
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