Exercise - 3.12

Choose the correct answer or the most suitable answer: . cos ◦ − sin ◦ = ( ) ( ) ( ) . If cos ◦ + sin ◦ = k , then cos ◦ is equal to ( ) k ( ) − k ( ) ± k ( ) − k . The maximum value of sin x + cos x + sin x + cos x is ( ) + ( ) + ( ) ( ) .

+ cos π + cos π + cos π + cos π ( ) ( ) ( ) ( ) . If π < θ < π , then q + + cos θ equals to ( ) − cos θ ( ) − sin θ ( ) cos θ ( ) sin θ . If tan ◦ = λ , then tan ◦ − tan ◦ + tan ◦ tan ◦ = ( ) − λ λ ( ) + λ λ ( ) + λ λ ( ) − λ λ . cos ◦ + cos ◦ + cos ◦ + .

. . + cos ◦ = ( ) ( ) ( ) − ( ) . Let f k ( x ) = k sin k x + cos k x where x ∈ R and k ≥ .

Then f ( x ) − f ( x ) = ( ) ( ) ( ) ( ) . Which of the following is not true? ( ) sin θ = − ( ) cos θ = − ( ) tan θ = ( ) sec θ = . cos θ cos φ + sin ( θ − φ ) − sin ( θ + φ ) is equal to ( ) sin ( θ + φ ) ( ) cos ( θ + φ ) ( ) sin ( θ − φ ) ( ) cos ( θ − φ )