surface curved shape Complete noob in Math here. 
I have a surface that I need to calculate the surface area from This shape (the surface IN the red line)
I understand that I can divide the 'room' in different shapes to get the right surface area, the only thing I don't understand is the right curved part of the room.
My knowledge of math isn't very good and I understand how to calculate the surface area of basic shapes (circle, triangle, cone, etc.) but I have no idea how to devide the room to calculate the curved shape.
Can you guys please help me/point me in the right direction? since I'm little to desperate.
Thanks in advance,
Tim
 A: Let's assume you know that the curved arc is in fact an arc of a circle, centered at the point $P$ (to the left of the diagram shown) where the long horizontal wall $AB$, if extended past the point $C$ where it meets the vertical wall, would meet the extension of the longer slanted wall $DE$.  
Then the shape you need the area of consists of a wedge of a circle $DPE$, plus the little rectangle (of area about $3\cdot 3.5 = 10.5$ at the lower left of the diagram, minus triangle $PBE$ which is to the left of the diagram.
It is not hard to find the $x$ coordinate of $P$ (the $y$ coordinate is zero, taking line $ABCP$ to be the line $y=0$):  Look at the slope of line $DE$ and the height at $E$ and the distance is height over slope.  It is also easy to find the area of triangle $PBE$ since you know the base and the height.
The wedge is almost as easy.  Angle $\theta = \angle DPE$ is the arctangent of the slope.  Express that in radians.  Then the area of the wedge is $\theta r^2$ where $r$ is the radius of the circle $r = PA = PD$.
