Question

Difficulty: MediumProperties of Quadrilaterals

Kite WXYZWXYZ has perpendicular diagonals WYWY and XZXZ that intersect at point MM. Diagonal WYWY bisects diagonal XZXZ such that XM=MZ=8XM = MZ = 8 centimeters. If WM=6WM = 6 centimeters and MY=15MY = 15 centimeters, what is the perimeter of kite WXYZWXYZ, in centimeters?

  1. A
    27
  2. B
    46
  3. 54Answer
  4. D
    68
  5. E
    74

Answer

The perimeter of kite WXYZWXYZ is 54 centimeters.
The correct answer is 54. The perpendicular diagonals of a kite form four interior right triangles. Using the legs WM=6WM = 6 cm and XM=8XM = 8 cm, the upper side WXWX is 62+82=10\sqrt{6^2 + 8^2} = 10 cm. Using the legs MY=15MY = 15 cm and XM=8XM = 8 cm, the lower side YXYX is 152+82=17\sqrt{15^2 + 8^2} = 17 cm. Summing all four outer sides (10+10+17+1710 + 10 + 17 + 17) gives a total perimeter of 54 cm.

Step-by-Step Solution

1
Identify key geometric properties of the kite's diagonals.
The diagonals WYWY and XZXZ are perpendicular at intersection point MM, creating four right triangles inside the kite.
By definition, the diagonals of a kite are perpendicular to each other.
2
Calculate the lengths of the upper pair of equal sides (WXWX and WZWZ).
WX=WM2+XM2=62+82=36+64=100=10 cmWX = \sqrt{WM^2 + XM^2} = \sqrt{6^2 + 8^2} = \sqrt{36 + 64} = \sqrt{100} = 10\text{ cm}. Since WZ=WXWZ = WX, WZ=10 cmWZ = 10\text{ cm}.
Apply the Pythagorean theorem to right triangle WMXWMX with legs of length 6 cm and 8 cm.
3
Calculate the lengths of the lower pair of equal sides (YXYX and YZYZ).
YX=MY2+XM2=152+82=225+64=289=17 cmYX = \sqrt{MY^2 + XM^2} = \sqrt{15^2 + 8^2} = \sqrt{225 + 64} = \sqrt{289} = 17\text{ cm}. Since YZ=YXYZ = YX, YZ=17 cmYZ = 17\text{ cm}.
Apply the Pythagorean theorem to right triangle YMXYMX with legs of length 15 cm and 8 cm.
4
Compute the total perimeter of kite WXYZWXYZ.
Perimeter=WX+WZ+YX+YZ=10+10+17+17=54 cm\text{Perimeter} = WX + WZ + YX + YZ = 10 + 10 + 17 + 17 = 54\text{ cm}.
Sum the lengths of all four exterior sides.

Key Concept

Properties of Kite Diagonals and Pythagorean Theorem
Estimated Time:1m 15s
Rate this question