Volume of solid of Revolution (1 Viewer)

[Triage]

The are bounded by the curve y=cos(2x), the line x=pi/12, the x axis and in the first quadrant is rotated about the x axis. Find the volume of solid of revolution.

Is this not an infinite volume?

 

[Carrotsticks]

The are bounded by the curve y=cos(2x), the line x=pi/12, the x axis and in the first quadrant is rotated about the x axis. Find the volume of solid of revolution.

Is this not an infinite volume?

It's not, because it's the area bounded by the curve and the line x=pi/12.

 

[Triage]

so the limits of integration are 0 and pi/12?

 

[Carrotsticks]

Yep!

 

[Triage]

In my test they said that they were pi/12 and pi/4 because the y axis is never mentioned in the question.

 

[braintic]

In my test they said that they were pi/12 and pi/4 because the y axis is never mentioned in the question.

They are right. The limits should be pi/12 and pi/4.
But why did they mention the first quadrant at all?

And I get tired of teachers/tutors describing 'areas' being rotated. An area in maths is a number with units. A 'region' is being rotated.