The easiest way to find the perimeter of a rectangle if only one side is given is to use the formula for the perimeter of a rectangle:-
Perimeter = 2(Length + Width).

P = 2(l+w).

•If we only know the length or the width of the rectangle, we can still use this formula by using the given side as either the length or the width.

●For example, if we only know the length of the rectangle, we can use it as the length in the formula and solve for the width using algebra. Once we have both the length and the width, we can plug them into the formula to find the perimeter.

•To prove that a trapezium has angles, we can use the fact that a trapezium is a quadrilateral with one pair of parallel sides. Since a quadrilateral has a total of four angles, and two of the sides of a trapezium are parallel, the opposite angles will be equal. This means that we can divide the trapezium into two triangles by drawing a diagonal from one vertex to the other. Each of these triangles has three angles, and since the opposite angles of the trapezium are equal, the two triangles will have one common angle. This common angle, along with the other two angles from each triangle, forms the four angles of the trapezium. Therefore, we can conclude that a trapezium has angles.

Hope it helps

• This reply was modified 1 year, 3 months ago by  Daniel Die.