Select the INCORRECT formula from the following options:

1. $\csc^{2} heta - \cot^{2} heta = 1$
2. $\sin^{2} heta + \cos^{2} heta = 1$
3. $\sec^{2} heta + \cos^{2} heta = 1$
4. $\sec^{2} heta - an^{2} heta = 1$

Question

Select the INCORRECT formula from the following options:

1. $\csc^{2} 	heta - \cot^{2} 	heta = 1$
2. $\sin^{2} 	heta + \cos^{2} 	heta = 1$
3. $\sec^{2} 	heta + \cos^{2} 	heta = 1$
4. $\sec^{2} 	heta - 	an^{2} 	heta = 1$

Accepted Answer

**Solution:**

1. The three main Pythagorean trigonometric identities are:

- $\sin^{2} 	heta + \cos^{2} 	heta = 1$
   - $\sec^{2} 	heta - 	an^{2} 	heta = 1$
   - $\csc^{2} 	heta - \cot^{2} 	heta = 1$

2. The third option, $\sec^{2} 	heta + \cos^{2} 	heta = 1$, is incorrect because the correct identity involving $\sec^{2} 	heta$ is:

$$\sec^{2} 	heta - 	an^{2} 	heta = 1$$

3. Therefore, option 3 is the incorrect formula.

**Answer:** Option 3: $\sec^{2} 	heta + \cos^{2} 	heta = 1$

Answer

Answer

Answer