Question

Show that:
(i) tan 10° tan 15° tan 75º tan 80° = 1
(ii) sin 42° sec 48° + cos 42° cosec 48° = 2
(iii)
sin 26° cos 26°
sec 64º. cosec 64°
​

Answer 1

Answer:

(i) tan 10°+ cot (90°-10°)=cot 80°=$\frac{1}{tan 80°}$

tan 15°+ cot (90°-15°)=cot 75°=$\frac{1}{tan 75°}$

therefore the equation reduces to,

[1/(tan 80°)][tan 80°][1/ tan 75°][tan 75°]

which cancel each other to give 1 as the answer.

I'm very sorry but I have no clue about the others.