Respuesta :
We know that: sin Ф = cos(π/2 - Ф) ↔ sin Ф = cos(90° - Ф)
Then:
sin 42° = cos(90° - 42°) = cos 48°
IF sin 42° = 2/3, the cos 48° = 2/3
Then:
sin 42° = cos(90° - 42°) = cos 48°
IF sin 42° = 2/3, the cos 48° = 2/3
sinα=cos(90-α) is a basic identity.
if sin42=2/3 then cos(90-42)=2/3 as well (90-42=48)
if sin42=2/3 then cos(90-42)=2/3 as well (90-42=48)