What is square ?
A square is a rhombus with four equal angles of 90.
Properties :
Problem 1 :
The square ABCD, find each length or angle measure.
1) BX 2) AX 3) DB 4) AC |
5) AB 6) BC 7) ∠AXB 8) ∠XAB |
Solution :
1) In square, the diagonal will bisect each other. So, BX = 8.5
2) Diagonals are equal, AX = 8.5
3) DB = 2DX, DB = 2(8.5) ==> 17
4) Diagonals are equal. So AC = 17
5) AB = 19
6) BC = 19
7) Diagonals will bisect each other at right angle, ∠AXB = 90
8) Diagonals will bisect the vertex angle, ∠XAB = 45
Problem 2 :
Classify the special quadrilateral. Then find the values of x and y.
Solution :
Since all sides are equal and angles at vertex is 90 degree. The given shape is square.
AB = DC 5x - 4 = 2y + 4 5x - 2y = 4 + 4 5x - 2y = 8 ------(1) |
AD = BC 5y + 1 = 3x 3x - 5y = 1 3x - 5y = 1 ------(2) |
(1) ⋅ 5 ==> 25x - 10y = 40
(2) ⋅ 2 ==> 6x - 10y = 2
(1) - (2)
19x = 38
x = 38/19
x = 2
By applying x = 1 in (1), we get
5(2) - 2y = 8
10 - 2y = 8
-2y = 8 - 10
-2y = -2
y = 1
Problem 3 :
For the square ABCD, find the missing values.
1) x 2) y |
3) AD 4) DB |
Solution :
Diagonals will bisect each other.
18 = 2x + 2y
Dividing by 2 on both sides.
9 = x + y
x + y = 9 ----(1)
All sides will be equal.
AB = AD
30 = 2x + 5y
2x + 5y = 30 ----(2)
(1) ⋅ 2 - (2) ==> (2x + 2y) - (2x + 5y) = 9 - 30
2y - 5y = -21
-3y = -21
y = 7
Problem 4 :
The diagonals of square DEFG intersect at H. Given that EH = 5, find the indicated measure.
1) ∠GHF 2) HF |
3) ∠DGH 4) DE |
Solution :
1) ∠GHF = 90 degree
2) HF = 5
3) ∠DGH = 45 degree
4) In triangle DHE,
(DE)^{2} = DH^{2} + HE^{2}
DE^{2} = 5^{2} + 5^{2}
DE^{2} = 25 + 25
DE = √50
DE = 5√2
Problem 5 :
ABCD is a given rectangle with length as 80 cm and breadth as
60 cm. P, Q, R, S are the mid points of sides AB, BC, CD, DA
respectively. A circular rangoli of radius 10 cm is drawn at the center as shown in figure given below. Find the area of shaded portion.
Solution :
DC = 80 cm, DR = 40 cm
DA = 60 cm, DS = 30 cm
In triangle DRS,
RS^{2} = DR^{2} + DS^{2}
RS^{2} = 40^{2} + 30^{2}
RS^{2} = 1600 + 900
RS^{2} = 2500
RS = 50
RS = PQ = SP = RQ
Area of square PQRS = 2500
Area of circle = πr^{2}
radius = 5 cm
= 3.14 (5)^{2}
= 3.14(25)
= 78.5
Area of shaded portion = 2500 - 78.5
= 1921.5 cm^{2}
Problem 6 :
A large square is made by arranging a small square surrounded by
four congruent rectangles as shown in figure given below. If the perimeter of
each of the rectangle is 16 cm, find the area of the large square.
Solution :
Perimeter of the rectangle = 16 inches
2(l + b) = 16
l + b = 8
Side length of the square = l + b
Area of square = (l + b)^{2}
= 8^{2}
= 64
Problem 7 :
ABCD is a square with AB = 15 cm. Find the area of the square BDFE.
Solution :
ABCD is a square, here BD is the diagonal of the square.
BD^{2} = AB^{2} + AD^{2}
BD^{2} = 15^{2} + 15^{2}
BD^{2} = 450
BD = 15√2
Area of square BDEF = BD^{2}
= (15√2)^{2}
= 225(2)
= 450
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