# Wronskian help

#### physstudent1

1. Homework Statement
take the wronskian of [cos(theta)]^2 and 1+cos(2theta)

2. Homework Equations

3. The Attempt at a Solution
so I set up the determinant

[cos(theta)]^2 1+cos(2theta) as my y1 and y2 respectively and
-2cos(theta)sin(theta) and -sin(2theta) as my y1 and y2 prime respectively

i get my determinant to be -2cos(theta)sin(theta)*[cos(theta)]^2 +2cos(theta)sin(theta)*(1+cos(2theta)) the answer in the back says it should be 0. So I'm assuming I have to do something with basic trig identities to get it to 0? I can't seem to get it to go to 0 though I've been trying for 30 minutes :(. Can anyone offer some insight?

Related Calculus and Beyond Homework Help News on Phys.org

#### AEM

Gold Member
1. Homework Statement
take the wronskian of [cos(theta)]^2 and 1+cos(2theta)

2. Homework Equations

3. The Attempt at a Solution
so I set up the determinant

[cos(theta)]^2 1+cos(2theta) as my y1 and y2 respectively and
-2cos(theta)sin(theta) and -sin(2theta) as my y1 and y2 prime respectively

i get my determinant to be -2cos(theta)sin(theta)*[cos(theta)]^2 +2cos(theta)sin(theta)*(1+cos(2theta)) the answer in the back says it should be 0. So I'm assuming I have to do something with basic trig identities to get it to 0? I can't seem to get it to go to 0 though I've been trying for 30 minutes :(. Can anyone offer some insight?
For one thing, I think your y2 prime should be -2sin(2 theta). (You briefly forgot the chain rule).

#### physstudent1

...wow I am an idiot! thanks I got it to simplify to 0 now haha sigh.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving