The perimeter of the rectangle is 62m. Find its sides if the area of the rectangle is 210m2.
1) Let x meters be the length of the rectangle, y meters – its width.
2) Then (x * y) m ^ 2 is the area of the rectangle, which, according to the condition of the problem, is 210 m ^ 2.
3) (2 * (x + y)) m – the perimeter of the rectangle, which is 62 m.
4) Let’s solve the system of equations:
x * y = 210;
2 * (x + y) = 62.
Let us express x:
x = 210 / y.
Substitute the x value in the second equation:
2 * (210 / y + y) = 62;
420 + 2y ^ 2 = 62y;
y ^ 2 – 31y + 210 = 0.
D = (-31) ^ 2 – 4 * 1 * 210 = 961 – 840 = 121.
y1 = (- (- 31) + 11) / 2;
y1 = (31 + 11) / 2;
y1 = 21;
y2 = (- (- 31) – 11) / 2;
y2 = (31 – 11) / 2;
y2 = 10.
Let’s find the values of x:
x1 = 210 / y1 = 210/21 = 10 m;
x2 = 210 / y2 = 210/10 = 21 m.
Answer: 10 meters and 21 meters; 21 meters and 10 meters.