Two of them
no it is a 4 dimensional figure not a 3 dimensional figure * * * * * No. A quadrilateral is a two dimensional figure. It has a length and a breadth and no more.
A diagonal --Algebra 2 Teacher
A quadrilateral is an object formed by four straight lines - two of which meet at an angle. A diagonal is one of the lines which go from one angle to the one other angle in the quadrilateral which it is not already connected to. If the angles of the quadrilateral are A, B, C and D, and A is connected by a straight line to B and D then the diagonal is a line between A and C. A--B | \ | D--C
ya it will........
You can divide a quadrilateral up into as many triangles as you want, but at least two.
A quadrilateral, in general, is not a parallelogram. If it is a parallelogram then you will have some additional information about its sides and angles. If you do not have such information it is not possible to prove that it is a parallelogram. Draw a diagonal which will divide the quadrilateral into two triangles and use the additional information that you have to show that the triangles are congruent. This can then be used to show equality of sides or of angles: the latter can then be used to show that sides are parallel. Note that the choice of which diagonal may influence how (if at all) you proceed.