# polar coordinatesWatch

#1
Can someone show me how to do the question below please.

The finite region R is bounded by an arc of the curve with equation r=acos3θ and the half-lines with equations θ=-π/6, θ=π/6. Find the area of T, given that a>0.

Is it 0.5∫aÂ²cosÂ²3θ dx between the two limits ? If so, what do I do now?

Thanks
0
quote
12 years ago
#2
(Original post by dhokes)
Can someone show me how to do the question below please.

The finite region R is bounded by an arc of the curve with equation r=acos3θ and the half-lines with equations θ=-π/6, θ=π/6. Find the area of T, given that a>0.

Is it 0.5∫aÂ²cosÂ²3θ dx between the two limits ? If so, what do I do now?

Thanks
Yes. aÂ² is a constant so can be taken outside the integral. I think the integral is the same as integrating between θ=0 and θ=π/6 and multiplying by 2. Then write cosÂ²3θ in terms of cos6θ.
0
quote
12 years ago
#3
I get pi a2/12
0
quote
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• University of Lincoln
Mini Open Day at the Brayford Campus Undergraduate
Wed, 19 Dec '18
• University of East Anglia
Fri, 4 Jan '19
• Bournemouth University
Wed, 9 Jan '19

### Poll

Join the discussion

Yes (173)
67.58%
No (83)
32.42%