Question

Ребята , решите 10 задание . Зарание спасибо. ^^

Answer 1

=√18*(cos²(7π/8)-sin²(7π/8))=√18*cos(2*(7π/8)=√18*cos(7π/4)=
=√18*cos(8π/4-π/4)=√18*cos(2π-π/4)=√18*cos(π/4)=√18*(√2/2)=√36/2=6/2=3