If sin A = cos B and A ≠ B then the relation between angles A and B is :

1. A + B = 180°

2. A - B = 90°

3. B - A = 90°

4. A + B = 90°

If A + B = 90°, the value of

$\dfrac{\text{cos A}}{\text{sin B}}\times \dfrac{\text{tan B}}{\text{cot A}}$ is :

1. 1

2. 2

3. sin A

4. cos B

The value of :

cosec 40° cos 50° + sin 50° sec 40° is:

1. 1

2. 2

3. 3

4. 0

In a triangle ABC, $\text{sec}\dfrac{A + C}{2}$ is equal to:

1. 0

2. $\text{sec}\dfrac{B}{2}$

3. cosec B

4. $\text{cosec}\dfrac{B}{2}$