10 сos ^2 a - sin ^2 a, если cos ^2 a = 3/5

Question

10 сos ^2 a - sin ^2 a, если cos ^2 a = 3/5

Answer 1

Cos ²a=3/5
sin²a=1-cos²a=1-(3/5)=(5-3)/5=2/5

10cos²a-sin²a=10*(3/5)-(2/5)=(30-2)/5=28/5