The value of + cot1° cot 2° cot 3°.... cot 90°, is

31

If cos θ = 2/3 then 2 sec²θ + 2tan²θ – 4 is equal to

32

tan 5° × tan 30° × 4 tan 85° is equal to

34

In Fig. 5.47, the value of cos ϕ is

35

In Fig. 5.48, AD = 4 cm BD = 3 cm and CB = 12 cm, find cot θ.