In the given diagram, △ ABC and △ DEF (not drawn to scale) are such that ∠C = ∠F and $\dfrac{AB}{DE} = \dfrac{BC}{EF}$, then

1. △ ABC ~ △ DEF

2. △ BCA ~ △ DEF

3. △ CAB ~ △ DEF

4. the similarity of given triangles cannot be determined.

In the adjoining diagram, ST is not parallel to PQ. The necessary and sufficient conditions for △ PQR ~ △ TSR is :

1. ∠PQR = ∠STR

2. ∠QPR = ∠TSR

3. ∠PQR = ∠TSR

4. ∠PRQ = ∠RST

In the adjoining figure, O is the center of the circle, and a semicircle is drawn on OA as the diameter. ∠APQ = 20°. The degree measure of ∠OAQ is :

1. 25°

2. 40°

3. 50°

4. 65°

In the given diagram, O is the center of the circle, and PQ is a tangent at A. If ∠ABC = 50°, then values of x, y and z respectively are :

1. 50°, 100°, 40°

2. 50°, 50°, 65°

3. 40°, 80°, 50°

4. 50°, 25°, 78°