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provta that
(sin239-sin221)(sin257-sin23)=3/16

suvrasanta chakraborty , 10 Years ago
Grade
anser 1 Answers
Sumit Majumdar

Last Activity: 10 Years ago

Solution:
We have:
sin(239)-sin(221)=2cos\left (\frac{239+221}{2} \right )sin\left (\frac{239-221}{2} \right )=2cos(230)sin(9)
similarly,
sin(257)-sin(23)=2cos\left (\frac{257+23}{2} \right )sin\left (\frac{257-23}{2} \right )=2cos(140)sin(117)
Simplifying this should give the required answer.
Regards
Thanks & Regards
Sumit Majumdar,
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