Question

2-sin^2т18°-cos^2 18°+ctg^2 45

Answer 1

2 -sin²18° -cos²18° +ctq²45°= 2 -(sin²18° +cos²18°) +(ctq45°)²=2 -1+1²=2.

Answer 2

=2-(sin^2 18+cos^2 18)+1^2=2-1+1=2