Advanced Geometry : Plane Geometry

Study concepts, example questions & explanations for Advanced Geometry

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Example Questions

Example Question #1 : Quadrilaterals

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The area of the rectangle is , what is the area of the kite?

Possible Answers:

Correct answer:

Explanation:

The area of a kite is half the product of the diagonals.

The diagonals of the kite are the height and width of the rectangle it is superimposed in, and we know that because the area of a rectangle is base times height.

Therefore our equation becomes:

.

We also know the area of the rectangle is . Substituting this value in we get the following:

Thus,, the area of the kite is .

Example Question #2 : Calculating The Length Of The Diagonal Of A Quadrilateral

Given: Quadrilateral  such that   is a right angle, and diagonal  has length 24.

Give the length of diagonal .

Possible Answers:

None of the other responses is correct.

Correct answer:

Explanation:

The Quadrilateral  is shown below with its diagonals  and .

. We call the point of intersection :

Kite

The diagonals of a quadrilateral with two pairs of adjacent congruent sides - a kite - are perpendicular; also,  bisects the  and angles of the kite. Consequently,  is a 30-60-90 triangle and  is a 45-45-90 triangle. Also, the diagonal that connects the common vertices of the pairs of adjacent sides bisects the other diagonal, making  the midpoint of . Therefore, 

.

By the 30-60-90 Theorem, since  and  are the short and long legs of 

By the 45-45-90 Theorem, since  and  are the legs of a 45-45-90 Theorem, 

.

The diagonal  has length 

.

Example Question #1 : How To Find The Length Of The Diagonal Of A Kite

Kite vt act

Using the kite shown above, find the length of the red (vertical) diagonal. 

Possible Answers:

Correct answer:

Explanation:

In order to solve this problem, first observe that the red diagonal line divides the kite into two triangles that each have side lengths of  and  Notice, the hypotenuse of the interior triangle is the red diagonal. Therefore, use the Pythagorean theorem: , where  the length of the red diagonal. 

The solution is: 







Example Question #1 : How To Find The Length Of The Diagonal Of A Kite

A kite has two perpendicular interior diagonals. One diagonal is twice the length of the other diagonal. The total area of the kite is . Find the length of each interior diagonal.

Possible Answers:

Correct answer:

Explanation:

To solve this problem, apply the formula for finding the area of a kite: 



However, in this problem the question only provides information regarding the exact area. The lengths of the diagonals are represented as a ratio, where 


Therefore, it is necessary to plug the provided information into the area formula. Diagonal  is represented by  and diagonal .

The solution is:











Thus, if , then diagonal  must equal 


Example Question #1 : How To Find The Length Of The Diagonal Of A Kite

A kite has two perpendicular interior diagonals. One diagonal has a measurement of  and the area of the kite is . Find the length of the other interior diagonal.

Possible Answers:

Correct answer:

Explanation:

This problem can be solved by applying the area formula: 



Since this question provides the area of the kite and length of one diagonal, plug that information into the equation to solve for the missing diagonal. 

Thus the solution is: 







Example Question #3 : How To Find The Length Of The Diagonal Of A Kite

A kite has two perpendicular interior diagonals. One diagonal has a measurement of  and the area of the kite is . Find the length of the other interior diagonal.

Possible Answers:

Correct answer:

Explanation:

This problem can be solved by applying the area formula: 



Since this question provides the area of the kite and length of one diagonal, plug that information into the equation to solve for the missing diagonal. 

Thus the solution is: 







Example Question #1 : How To Find The Length Of The Diagonal Of A Kite

A kite has two perpendicular interior diagonals. One diagonal has a measurement of  and the area of the kite is . Find the sum of the two perpendicular interior diagonals.

Possible Answers:

Correct answer:

Explanation:

First find the length of the missing diagonal before you can find the sum of the two perpendicular diagonals. 

To find the missing diagonal, apply the area formula: 




This question provides the area of the kite and length of one diagonal, plug that information into the equation to solve for the missing diagonal. 










Therefore, the sum of the two diagonals is: 

Example Question #1 : How To Find The Length Of The Diagonal Of A Kite

A kite has two perpendicular interior diagonals. One diagonal has a measurement of  and the area of the kite is . Find the sum of the two perpendicular interior diagonals.

Possible Answers:

Correct answer:

Explanation:

You must find the length of the missing diagonal before you can find the sum of the two perpendicular diagonals. 

To find the missing diagonal, apply the area formula: 




This question provides the area of the kite and length of one diagonal, plug that information into the equation to solve for the missing diagonal. 










Therefore, the sum of the two diagonals is: 

Example Question #1 : How To Find The Length Of The Diagonal Of A Kite

Kite vt act

The area of the kite shown above is  and the red diagonal has a length of . Find the length of the black (horizontal) diagonal. 

Possible Answers:

Correct answer:

Explanation:

To find the length of the black diagonal apply the area formula: 



Since this question provides the area of the kite and length of one diagonal, plug that information into the equation to solve for the missing diagonal. 

Thus the solution is: 







Example Question #6 : How To Find The Length Of The Diagonal Of A Kite

A kite has two perpendicular interior diagonals. One diagonal has a measurement of  and the area of the kite is . Find the length of the other interior diagonal.

Possible Answers:

Correct answer:

Explanation:

This problem can be solved by applying the area formula: 



Since this question provides the area of the kite and length of one diagonal, plug that information into the equation to solve for the missing diagonal. 

Thus the solution is: 







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