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  1. Home
  2. 12th grade
  3. Geometry
  4. Exercise : Complete proofs involving quadrilaterals

Complete proofs involving quadrilaterals Geometry

Find the missing step in the following reasoning in order to find the area of the trapezoid.

Step
1 Using the Pythagoras theorem we have: BF= \sqrt{5^2-3^2}=4
2 ....
3 S=\dfrac{1}{2}\left(AB+DC\right).FC = \dfrac{1}{2}\left(14+5\right).3
4 The area of the trapezoid is 28.5.
-

Find the missing step in the following reasoning in order to determine a of the parallelogram

Step
1 Since \overline{AB} and \overline{DC} are parallel, \widehat{C} and \widehat{DAB} are corresponding angles.
2 ....
3 \widehat{DAB} and a are supplementary.
4 a=180^\circ - 70^\circ = 110^\circ
-

Find the missing step in the following reasoning in order to find a.

Step
1 \widehat{BDC} and the 150 degree angle are supplementary.
2 ....
3 30^\circ+a + 90^\circ + 90^\circ=360^\circ
4 a=150^\circ
-

Find the missing step in the following reasoning in order to find the perimeter of the kite.

Step
1 The perimeter of the kite equals: P=2AD+2CD
2 .....
3 CD= 2OD= 6
4 P=2\left(9\right)+2\left(6\right)=30
-

Find the missing step in the following reasoning in order to find the area of the rhombus.

Step
1 The area of the rhombus equals: S=AC \times CD
2 BD=2OB=10
3 ....
4 AC=2AO=24
5 S=24 \times 10 = 240
-

Find the missing step in the following reasoning in order to find the area of the parallelogram.

Step
1 The area of the parallelogram equals: S=AH \times CD
2 .....
3 DC= DH+CH = 3+4= 7
4 S=7 \times 4=28
-

Find the missing step in the following reasoning in order to find the perimeter of the square.

Step
1 The perimeter of the square equals: 4x
2 ....
3 2x^2=9
4 x=3\dfrac{\sqrt{2}}{2}
5 P=4 \times 3\dfrac{\sqrt{2}}{2} = 6\sqrt{2}
-
See also
  • Course : Quadrilaterals
  • Exercise : Use the general properties of quadrilaterals to determine measures of angles or lengths
  • Exercise : Identify special quadrilaterals
  • Exercise : Determine lengths and angles in special quadrilaterals
  • Exercise : Calculate the area of special quadrilaterals
  • Exercise : Calculate the perimeter of special quadrilaterals
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