In a ΔABC, if a = 3 cm, b = 5 cm and c = 7 cm, find cos A, cos B, cos C.

In a ∆ABC, if , show that the triangle is right-angled.

Solve the triangle in which a = 2 cm, b = 1 cm and c = cm.

If the angles of a triangle are in the ratio 1 : 2 : 3, prove that its corresponding sides are in the ratio .

Two boats leave a port at the same time. One travels 60 km in the direction N 50⁰ E while the other travels 50 km in the direction S 70⁰ E. What is the distance between the boats?