Evaluate the following. sin 25° sin 65° – cos 25° cos 65°.

If sin$$\phi$$ - cos$$\phi$$ = 0, then the value of sin$$^4 \phi$$ + cos$$^4 \phi$$ + tan$$^2 \phi$$ is:​

If sin 3 θ = cos (θ – 6°), then θ is:

If sin(3A – 20°) = cos(20° – 3B), then the value of A – B is:

​All trigonometric functions are periodic. What is the period of cos x ?​

​$$cos^231°+cos^259°$$​ is equal to:

Express: sin58° + cos82° in terms of Trigonometric ratios of angles between 0° and 45°.

If cot 35° = 2-$$\sqrt3$$​ then the value of tan 35° cot 55° + tan 55° cot 35° is:

​$$\frac{ 3 \sin 58^\circ}{5\cos 32^\circ}+\frac{2cos62^\circ}{5\sin28^\circ}$$​ is equal to: