# absolute value with sinθ

• Jan 20th 2013, 09:44 AM
happymatthematics
absolute value with sinθ
I encountered an question of calculation of volume.
The following is a part of the solution.
I don't know why the highlighted sinθ has an absolute value sign.
Can anyone explain to me? Thank you.

Attachment 26621
• Jan 20th 2013, 01:31 PM
HallsofIvy
Re: absolute value with sinθ
Because $\sqrt{a^2}= |a|$, not a.

For example, $\sqrt{(-2)^2}= \sqrt{4}= 2$, not $-2$.
• Jan 20th 2013, 05:54 PM
happymatthematics
Re: absolute value with sinθ
Thank you, HallsofIvy.