How do you measure sq.ft. in a room that’s not square?

[Mike]

I am standing in a doorway that is 3 ft wide. From there a wall goes right at a 45 degree angle for 10 ft. The left wall also goes to the left at a 45 degree angle also for 10 ft. Both far ends of the 10 ft wall are 12 ft. apart.

I need to know(learn) how to calculate the square footage of rooms like this. Please don’t just put the answer, I need to learn how to to it. Any help would be greatly appreciated.

[Reed Schwimmer]

From your description, it seems that the room is a triangle (forget the lack of a third corner due to the doorway). In which case, the area is equal to 1/2 base x height. In this case, the base can be the 12 ft measurement. The height is the measurement from the doorway to the far wall, I’m assuming that this line will be perpendicular to the fall wall. So then the area is (0.5 x 12) x height.

[rocket scientist]

The object would be to make the area into a square(s) or rectangle(s). Since you have a 3 ft opening to start with, that would be the short side of your first rectangle 3.0 by X (unknown distance to the 12 ft line) Then on either side of this rectangle you would have 2 right triangles, which if you flip one over and put it against the other would form another rectangle. Subtracting the 3 ft from the 12 ft gives you 9 ft or 4.5ft on either side to form the short sides of the 2 right triangles. Flip one triangle, put it against the other and you have a rectangle 4.5 by X (same as the other unknown)….join that to the first rectangle and you have 7.5 by X . Now you can either measure from the doorway to the 12ft line to find “X” or revert back to highschool trig to find “X” (8.9303″) and multiply length X width

[Marshall Ham]

I have a drive way that I want to poor some concert it is 15×13.5. what would be my square footage?

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