Question

Which of the following is not a fundamental​ identity?

Answer 1

Answer:b

Step-by-step explanation:

Given

Option a is correct because it is Pythagorean identity

$1=\sin^2\theta +\cos^2\theta$

Option b is incorrect because

$\tan \theta =\frac{\sin \theta }{\cos \theta }$

Option c and d are correct because c is Pythagorean identity .