All Intermediate Geometry Resources
Example Questions
Example Question #32 : Parallelograms
Given: Regular Pentagon with center . Construct segments and to form Quadrilateral .
True or false: Quadrilateral is a parallelogram.
True
False
False
Below is regular Pentagon with center , a segment drawn from to each vertex - that is, each of its radii drawn.
The measure of each angle of a regular pentagon can be calculated by setting equal to 5 in the formula
and evaluating:
Specifically,
By symmetry, each radius bisects one of these angles. Specifically,
By the Same-Side Interior Angles Theorem, consecutive angles of a parallelogram are supplementary - that is, their measures total . However,
,
violating these conditions. Therefore, Quadrilateral is not a parallelogram.
Example Question #371 : Plane Geometry
Given: Quadrilateral such that and .
True or false: It follows that Quadrilateral is a parallelogram.
False
True
False
, making and supplementary. By the Converse of the Same Side Interior Angles Theorem, , it does follow that . However, without knowing the measures of the other two angles, nothing further can be concluded about Quadrilateral . Below are a parallelogram and a trapezoid, both of which have these two angles of these measures.
Example Question #12 : How To Find An Angle In A Parallelogram
Given: Parallelogram such that and .
True or false: It follows that Parallelogram is a rectangle.
False
True
True
By the Same-Side Interior Angles Theorem, consecutive angles of a parallelogram can be proved to be supplementary - that is, their angle measures total . Specifically, and are a pair of supplementary angles. Since they are also congruent, it follows that both are right angles. For the same reason, and are also right angles. The parallelogram, having four right angles, is a rectangle by definition.
Example Question #371 : Plane Geometry
Given: Rectangle with diagonals and intersecting at point .
True or false: must be a right angle.
True
False
False
The diagonals of a parallelogram are perpendicular - and, consequently, is a right angle. - if and only if the parallelogram is a rhombus, a figure with four sides of equal length. Not all rectangles have four congruent sides. Therefore, need not be a right angle.
Example Question #202 : Quadrilaterals
Given: Parallelogram such that .
True or false: Parallelogram must be a rectangle.
False
True
True
A rectangle is a parallelogram with four right angles.
Consecutive angles of a parallelogram are supplementary. If one angle of a parallelogram is given to be right, then its neighboring angles, being supplementary to a right angle, are right as well; also, opposite angles of a parallelogram are congruent, so the opposite angle is also right. All four angles must be right, making the parallelogram a rectangle by definition.
Example Question #371 : Intermediate Geometry
Find the perimeter of the following box in inches:
The answer is .
You can find the perimeter by adding all of its respective sides as such:
.
Adding like terms will result in
If you chose , you multiplied the two sides to find the area.
If you chose , you only added two sides. Perimeter involves all 4 sides; so double the width and length.
Just remember, the width is 12 added to . Not 12 times the side of .
Example Question #31 : Parallelograms
A parallelogram has an area of . If the height is , what is the length of the base?
Cannot be determined
If the area of a parallelogram is given as with a height of , we can refer back to the equation for the area of a parallelogram:
, where is height and is the length of the base.
This very quickly becomes a problem of substituting in values and finding the value of an unknown variable, in this case, :
Example Question #371 : Intermediate Geometry
A parallelogram has a base of and an area of . What is the height of the parallelogram?
In order to find the height of this parallelogram apply the formula:
Example Question #4 : How To Find The Length Of The Side Of A Parallelogram
A parallelogram has a height of and an area of . What is the length of the base of the parallelogram?
To find the missing side of this parallelgram apply the formula:
Thus, the solution is:
Example Question #2 : How To Find The Length Of The Side Of A Parallelogram
Given that a parallelogram has a height of and an area of . Find the base of the parallelogram.
In order to find the base of this parallelogram apply the formula:
Thus, the solution is:
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