Question

1)Să se calculeze:sin de 15 grade,cos de 105 grade,sin de 135 de grade,cos de 210 grade

Answer 1

Salut,

sin(15grade)=sin(45grade-30grade)

sin(45grade)cos(30grade)-cos(45grade)sin(30grade)

✓2/2×✓3/2-✓2/2×1/2

✓6/4-✓2/4=(✓6-✓2)/4

cos(105grade)=cos(45grade+60grade)

cos(45grade)cos(60grade)-sin(45grade)sin(60grade)

✓2/2×1/2-✓2/2×✓3/2

✓2/4-✓6/4=(✓2-✓6)/4

sin(135grade)=✓2/2

cos(210grade)= - ✓3/2

Spor!