Find The Value of Tan 40°

Answer : We can express tan 40° as tan (30 + 10). 

We will apply the following formula here:-

tan (A+B) = (tan A + tan B) / (1 – tan A tan B)

tan (30+10) = (tan 30 + tan 10) / (1 – tan 30 tan 10)

Substitute the approximate values as below:-

tan 40°= (0.57735 + 0.176326) / (1 – 0.1018)

tan 40°= (0.753676) / (0.8982)

tan 40°= 0.8391

Therefore, the value of  tan 40° is 0.8391.