Question

7. In △ABC, AB = AC = 15 cm, BC = 18 cm. Find (i) cos ∠ABC (ii) sin
∠ACB.
Hint: Draw AD perpendicular to BC, then D is mid-point of BC, so BD = 9 cm. By
Pythagoras theorem, AD = 12 cm.​

Answer 1

Answer:

AB = AC = 15 cm, BC = 18 cm.

By Pythagoras theorem,

∠ABC,

cos B = BD/AB = 9/15 = 3/5

cosB = 3/5

∠ACB.

sin C = AD/AC = 12/15 = 4/5

sin C = 4/5