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The area of a circle with radius 7 cm is (take π=22/7):
154 cm²
44 cm²
77 cm²
144 cm²
154 cm²
Since the radius is a multiple of 7 (r=7), the area πr2=722×7×7=22×7=154, which can be calculated mentally in seconds.
Radius of the circle r = 7 cm, value of pi = 22/7
Area=πr2
Since the radius is a multiple of 7 (r=7), the area πr2=722×7×7=22×7=154, which can be calculated mentally in seconds.
Confusing the formula for the area of a circle (πr2) with the formula for the circumference (2πr).
Identify Given Data
Note down the radius of the circle given in the problem statement: r=7 cm.
r=7 cm
State the Area Formula
Recall the standard formula for the area of a circle in terms of its radius: Area=πr2.
Area=πr2
Substitute Values and Calculate
Substitute π=722 and r=7 into the formula: Area=722×72=722×49=22×7=154.
Area=722×7×7=154 cm2
A is correct because the calculated area of the circle with radius 7 cm is 154 cm².
Mensuration questions in CBT-1 often test standard geometric formulas combined with basic arithmetic shortcuts involving multiples of 7 for π.