# When do we learn trig sub?

1. Sep 26, 2008

### vinnie

I am in calc 2 right now, and we were told we will not have time to learn trigonmetric substitution. There is a section on it in the single variable book we are using. Is trig sub usually taught in calculus 3 or should I learn it on my own? Is it a difficult concept to self-teach?

2. Sep 26, 2008

### Topher925

I learned it in high school. Its not a difficult concept to learn, but it does take some memorization and a lot of practice in order to recognize the tricks that some problems will have.

3. Sep 26, 2008

### Howers

Calc 2 is the typical place. Learn it over the summer. It wont be done in calc 3.

4. Sep 26, 2008

### symbolipoint

You will not have time to learn it in your Calculus 2 course? NONSENSE! Learn it on your own. What kind of Calculus 2 course are you in? If an engineering or mathematics track course, then you are being cheated.

Basically, you are applying the pythagorean theorem and substituting from the relationship of variables and expressions based on the labeling which can be done on the triangle. This does not require much memorization, or nearly none.

5. Sep 26, 2008

### Nick M

I learned Trig Sub in Calculus II. It's really something you can cover in a few hours on your own. Make sure you learn Integration by Partial Fractions too (often included near Trig Sub in text books - in the sections on alternative integration techniques). If you know your Trig identities from Pre-Calculus, Trig-Sub will be a very logical method.

Last edited: Sep 26, 2008
6. Sep 26, 2008

### Troponin

I've seen programs that attempt to cover basic integration techniques (substitution, by parts, trig substitution) in the last weeks of Calc I. It is usually blocked in with the first sections of calc II (see above, along with basic area and volume integration).

As everyone else has said, it's mostly just basic memorization of some trig identities. Even with a few basic identities, you can usually u-substitute your way through the problem.