cosA=3/4then find value of32 sin(A/2) sin 5(A/2)
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32sin (A/2) sin (5A/2)
16 {2sin (A/2).sin (5A/2)}
=> 16 {cos2A-cos3A}
=> 16cos2A-16cos3A
use cos2A and cos3A formula
=> 16 {2cos^2A-1}-16 {4cos^3A-3cosA}
=>16cos^2A-16-64cos^3A+48cosA
now put cosA=3/4
=> 16 (3/4)^2-16-64 (3/4)^3+48 (3/4)
=> 9-16-27+36
=>2
16 {2sin (A/2).sin (5A/2)}
=> 16 {cos2A-cos3A}
=> 16cos2A-16cos3A
use cos2A and cos3A formula
=> 16 {2cos^2A-1}-16 {4cos^3A-3cosA}
=>16cos^2A-16-64cos^3A+48cosA
now put cosA=3/4
=> 16 (3/4)^2-16-64 (3/4)^3+48 (3/4)
=> 9-16-27+36
=>2
Anonymous:
16*4= 64 u written but 16*2 u not written
so answer was 32cos^2A-16-64cos^3A+48cosA
got it
yaar u answer is nyc but u forgot to multiply the term
just correct it
thanks but answer now not edit
hmmm okk anyway user can get it
ur all answers are very nice
sorry for that answer is 11
oh thans a lot
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