diketahui sinx=3/5dan cos y=12/13,x sudut tumpul dan y sudut lancip. nilai cos (x-y)

Trigonometri

sin x = 3/5  --> cos x = √(1 - sin² x) = √(1 - 9/25) = +_ 4/5
x lancip, cos x = 4/5

cos y = 12/13 --> sin x = 5/13

cos (x - y) = cos x cos y + sin x sin y
cos (x - y) = (4/5)(12/13) + (3/5)(5/13) =  48/65 + 15/65
cos (x - y)= 63/65
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