Sharon Sunil Asked a Question
April 13, 2020 11:57 pmpts 30 pts
IfA +B+C=3Pi/2 then cos 2A + cos 2B + Cos 2C is ? The answer is given in the booklet but i want a detail description step wise for better understanding
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  • Abhijeet Gaurav thankyou
    Here is the solution
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  • Narayan singh thankyou
    As A+B+C=3π/2, we have A+B=(3π/2−C) and cos(A+B)=cos(3π/2−C)=−sinC Hence cos2A+cos2B+cos2C =2cos(2A+2B/2)cos(2A−2B/2)+cos2C =2cos(A+B)cos(A−B)+cos2C =2cos(3π/2−C)cos(A−B)+1−2...
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