Question

KUIS TRIGONO

Tentukan nilai eksak dari sin 26° (bkn desimal)

Answer 1

Cos52= cos (105-53)
          = cos 105.cos53 + sin 105.sin 53
          = (3/5).cos (60+45) + (4/5).sin (60+45)
          = (3/5)(cos 60.cos 45-sin 60.sin 45)+(4/5)(sin 60.cos 45+cos 60.sin 45)
          = (3/5)((1/4)√2-(1/4)√6)+(4/5)((1/4)√6+(1/4)√2)
          = (1/20).(7√2 + √6)

sin (52/2) = √((1-cos 52)/2)
                = √((1-(1/20).(7√2 + √6))/2)
                = √((20-7√2-√6)/40)