1:
Use the fundamental trigonometric identity to show that :

(a) The triangle with sides 5cm, 12cm and 13 cm is a right-angled triangle.

(b) The triangle with sides 7cm, 15cm and 16cm is not a right-angled triangle.

2: Show that

(a) tan 75^o = sq 3+1/sq 3-1

(b) sin 15^o = sq3-1/2 sq 2.


Let me see the first to work out this questions.