sin(a+b) = sin a cos b +cos a sin b
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Answer:
Hi ,
Hi ,***************************
Hi ,***************************sin( A + B ) = sinAcosB + cosAsinB
Hi ,***************************sin( A + B ) = sinAcosB + cosAsinB**********************************
Hi ,***************************sin( A + B ) = sinAcosB + cosAsinB**********************************1 ) Here , we assume
Hi ,***************************sin( A + B ) = sinAcosB + cosAsinB**********************************1 ) Here , we assumeA = 45° , B = 30°
Hi ,***************************sin( A + B ) = sinAcosB + cosAsinB**********************************1 ) Here , we assumeA = 45° , B = 30°cos 15°
= cos ( 90 - 75 )
= cos ( 90 - 75 )= sin 75 °
= cos ( 90 - 75 )= sin 75 °= sin ( 45 + 30 )
= cos ( 90 - 75 )= sin 75 °= sin ( 45 + 30 )= sin45cos30 + cos45sin30
= cos ( 90 - 75 )= sin 75 °= sin ( 45 + 30 )= sin45cos30 + cos45sin30= ( 1/√2 )( √3/2 ) + ( 1/√2 ) ( 1/2 )
= cos ( 90 - 75 )= sin 75 °= sin ( 45 + 30 )= sin45cos30 + cos45sin30= ( 1/√2 )( √3/2 ) + ( 1/√2 ) ( 1/2 )= ( √3/2√2) + 1/2√2
= cos ( 90 - 75 )= sin 75 °= sin ( 45 + 30 )= sin45cos30 + cos45sin30= ( 1/√2 )( √3/2 ) + ( 1/√2 ) ( 1/2 )= ( √3/2√2) + 1/2√2= ( √3 + 1 )/2√2
= cos ( 90 - 75 )= sin 75 °= sin ( 45 + 30 )= sin45cos30 + cos45sin30= ( 1/√2 )( √3/2 ) + ( 1/√2 ) ( 1/2 )= ( √3/2√2) + 1/2√2= ( √3 + 1 )/2√2Therefore ,
cos15° = sin75° = ( √3 + 1 )/2√2
cos15° = sin75° = ( √3 + 1 )/2√2I hope this helps you.
cos15° = sin75° = ( √3 + 1 )/2√2I hope this helps you.: )
Formulas are in the attachment....Hope it helps...
I have added trick to remember it...hope you understand
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