sin²u + tan²u + cos²u/ sec u

simplify

To simplify the expression sin²u + tan²u + cos²u / sec u, we can use trigonometric identities.

1. Recall the Pythagorean identity for sine and cosine: sin²u + cos²u = 1. We can substitute this into our expression to simplify it.

(sin²u + tan²u) + cos²u / sec u

2. Next, recall the identity for tangent in terms of sine and cosine: tan u = sin u / cos u. We can substitute this into our expression as well.

(sin²u + sin²u / cos²u) + cos²u / sec u

3. Now, let's simplify the terms separately.

a. Simplifying the numerator of the first term: (sin²u + sin²u) = 2sin²u

b. Simplifying the denominator of the first term: / cos²u

c. Simplifying the second term: cos²u / sec u

Remember that sec u is the reciprocal of cos u, so sec u = 1 / cos u.

Substituting this into the second term: cos²u / (1 / cos u) = cos²u * cos u = cos³u

4. Finally, let's combine the simplified terms.

2sin²u / cos²u + cos³u

Now, the expression is simplified as 2sin²u / cos²u + cos³u.