Question

Cot theta*tan(90-theta)-sec(90-theta)*cosec thata+√3 tan 12° *tan 60°*tan 78°=?

Answer 1

tan(90-x)=cotx  &  sec(90-x)=cosecx
-->  equation becomes cot²(theta) - cosec²(theta)+ (3)
Note :- tan78=1/tan12  &   tan60 =√3  ---->   tan78*tan12=1 & √3*√3 =3 

By formula cosec²x² - cot²x = 1 --> cot²x - cosec²x = -1

Finally, -1+3 =(2)  Ans.

Answer 2

Answer:

Step-by-step explanation:

tan(90-x)=cotx  &  sec(90-x)=cosecx

-->  equation becomes cot²(theta) - cosec²(theta)+ (3)

Note :- tan78=1/tan12  &   tan60 =√3  ---->   tan78*tan12=1 & √3*√3 =3 

By formula cosec²x² - cot²x = 1 --> cot²x - cosec²x = -1

Finally, -1+3 =(2)  Ans.