Question

Evaluate : (i) sin 18°/cos 72° (ii) tan 26°/cot 64° (iii) cos 48° – sin 42° (iv) cosec 31° – sec 59°

Answer 1

SOLUTION
(i) sin 18°/cos 72°    = sin (90° - 18°) /cos 72°     = cos 72° /cos 72° = 1(ii) tan 26°/cot 64°    = tan (90° - 36°)/cot 64°    = cot 64°/cot 64° = 1(iii) cos 48° - sin 42°      = cos (90° - 42°) - sin 42°      = sin 42° - sin 42° = 0(iv) cosec 31° - sec 59°     = cosec (90° - 59°) - sec 59°     = sec 59° - sec 59° = 0

Answer 2

Sin 18/cos72 cos(90-72)/cos72
Cos72/sin72=1
Tan26/tan(90-74)=1
Cos48-sin42=sin(90-42)-sin42=0
Cosec31-Cosec(90-69)
Cose31-Cosec31=0