Page 173 - Start Up Mathematics_5
P. 173
Example 1: Find the perimeter of a rectangle whose length is 12 cm and breadth is 7 cm.
Solution: Length (l) = 12 cm, Breadth (b) = 7 cm A Challenge!
Perimeter = 2 × (l + b) The perimeter of a rectangle
= 2 × (12 cm + 7 cm) is 24 cm. If its length is
7 cm, find its breadth.
= 2 × 19 cm = 38 cm
Perimeter of a square side
Perimeter of square DEFG = DE + EF + FG + GD D E
= Side + Side + Side + Side
= 4 × Side side side
Perimeter of a square = 4 × Side G F
side
Side of a square = Perimeter
4
Example 2: Find the perimeter of a square whose sides measure 6 cm each.
Solution: Side = 6 cm
Perimeter = 4 × Side
= 4 × 6 cm = 24 cm
Example 3: Find the measure of the side of a square whose perimeter is 48 cm.
Solution: Perimeter = 48 cm
Side = Perimeter
4
= 48 cm = 12 cm
4
Perimeter of a triangle L
Perimeter of triangle LMN = LM + MN + NL
= a + b + c a c
Perimeter of a triangle = Side + Side + Side
M b N
Example 4: Find the perimeter of a triangle whose sides measure 4 cm, 6 cm and 5 cm.
Solution: a = 4 cm, b = 6 cm, c = 5 cm
Perimeter = a + b + c
= 4 cm + 6 cm + 5 cm = 15 cm
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