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If the side of an equilateral triangle is 10 cm, find its area (use 3тАЛ=1.732).
43.3 sq cm
86.6 sq cm
25.0 sq cm
50.0 sq cm
43.3 sq cm
Since the area is approximately 0.433├Чa2, simply square the side (100) and move the decimal point two places to the right (43.3).
Side of an equilateral triangle (a) = 10 cm, value of square root of 3 = 1.732.
Area=43тАЛтАЛ├Чa2
Since the area is approximately 0.433├Чa2, simply square the side (100) and move the decimal point two places to the right (43.3).
Confusing the area formula for an equilateral triangle with the perimeter formula or neglecting to square the side length before multiplying by the constant.
Identify given parameters
The side of the equilateral triangle is given as a=10┬аcm.
a=10
Select area formula
The area A of an equilateral triangle is calculated using the standard formula.
A=43тАЛтАЛ├Чa2
Substitute values and calculate
Substitute a=10 and 3тАЛ=1.732 into the formula: A=41.732тАЛ├Ч102=41.732тАЛ├Ч100.
A=0.433├Ч100=43.3
A is correct because the calculation 0.433├Ч100 results in 43.3┬аsq┬аcm.
This formula is a specific case of Heron's formula; memorizing this variant saves time in coordinate geometry and mensuration problems involving tiling.