Question

Sa se calculeze
sin 48+sin56+sin132+sin124

Answer 1

Sin48+sin 132+sin56+sin124=
2sin[(48+132)/2] *cos[(48-132)/2]+ 2sin [(56+124)/2]cos[(56-124)/2]=
=2sin180/2 *cos (-84)/2+2sin180/2 *cos (-68)/2=
2sin 90*cos 42+2sin 90*cos34=
=2*1*cos 42+2*1*cos 34=
2(2cos[(42+34)/2]*cos[(42-34)/2] =
2*2* cos76/2 *cos 8/2
4cos38cos4..... Cam asa ar trebui sa fie.... Sper sa intelegi ce am facut si cum am facut....