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A square can be constructed using a few known measurements.
 
The measurements are:
1. When the side is known.
 
2. When the diagonal is known
Method 1: When the side is known
Let us construct a square with 5 cm as its side. Let us also find the area of the square obtained.
 
Step 1: Draw a rough diagram for the measurements given.
 
1324_42.svg
 
Step 2: Draw a line segment AB of length 5 cm.
 
1324_43.svg
 
Step 3: With A as centre, draw a perpendicular line.
 
1324_44.svg
 
Step 4: With A as centre and with 5 cm as radius, draw an arc on the perpendicular line. Mark the intersection as D.
 
1324_45.svg
 
Step 5: With D as centre and with 5 cm as radius, draw an arc. Similarly, with B as centre and with 5 cm as radius, cut the existing arc. Mark the intersection as C.
 
1324_46.svg
 
Step 6: Join BC and CD to form the desired square.
 
1324_47.svg
 
To find the area of the square:
 
\text{Area of a square} = \text{Side} \times \text{Side}
 
\text{Area of a square} = \text{Side}^2
 
Here, \text{Side} = 5 cm.
 
Therefore, \text{Area of a square} = 5^2
 
= 25 cm^2
Method 2: When the diagonal is known
Let us construct a square with one of its diagonals as 10 cm. Let us also find the area of the square obtained.
 
Step 1: Draw a rough diagram with the measurements known.
 
1324_52.svg
 
Step 2: Draw a line segment AC of length 10 cm.
 
1324_48.svg
 
Step 3: Draw a perpendicular bisector to AC such that the bisector intersects AC at O.
 
1324_49.svg
 
Step 4: With O as centre and with 5 cm as radius, draw arcs on both sides of the perpendicular bisector. Mark the intersections as B and D.
 
1324_50.svg
 
Step 5: Join AB, BC, CD, and AD to form the desired square.
 
1324_51 (1).svg
 
To find the area of the square:
 
\text{Area of a square} = \text{Side} \times \text{Side}
 
\text{Area of a square} = \text{Side}^2
 
Here, side is unknown.
 
Therefore, we should measure the length of the side manually.
 
On measuring, we found that, \text{Side} = 7.1 cm
 
Now, \text{Area of a square} = 7.1^2
 
= 50.41 cm^2