You are Here: Home >< Maths

# how do i integrate... watch

1. 1. integrate cos(m.pi.x/L)cos(n.pi.x/L) between L and -L

and same integration but with sin insted of cos

2. integrate sin(m.pi.x/L)cos(n.pi.x/L) between L and -L and show it equals 0
1. integrate cos(m.pi.x/L)cos(n.pi.x/L) between L and -L

and same integration but with sin insted of cos

2. integrate sin(m.pi.x/L)cos(n.pi.x/L) between L and -L and show it equals 0
For one use the identity

2 cosP cosQ = cos(P+Q) + cos (P-Q)

for suitable P and Q.

For the second one, determine a similar identity using

sin(P+Q) + sin (P-Q).

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 25, 2005
Today on TSR

### University open days

Wed, 21 Nov '18
• Buckinghamshire New University
Wed, 21 Nov '18
• Heriot-Watt University
Wed, 21 Nov '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams