A square board 20 cm side has a corner triangle removed (right triangle, legs 5 cm each). What percent of the board remains?
Show answer & explanation
Correct answer: C
Explanation
Given:
Side of the square = 20 cm
Sides of the triangle (right-angled) = 5 cm, 5 cm
According to the formulas:
Area of the square = a²
Area of the triangle = (1/2) × a × b
Percentage = (Remaining / Original) × 100
Area of the square = 20² = 400
Area of the triangle = (1/2) × 5 × 5 = 12.5
Remaining area = 400 − 12.5 = 387.5
Percentage