The sides of a rectangle are in the ratio 4 : 3. If the perimeter of the rectangle is 210, find its area

2700

Step-by-step explanation:

Perimeter of rectangle= 2(length +breadth)

2(length +breadth)= 210

length +breadth= 210 ÷2

length +breadth= 105

Since the length of the rectangle is usually taken to be the longer side of the rectangle,

length: breadth= 4: 3

breadth

= 45

length +breadth= 105

length +45= 105

length

= 105 -45

= 60

Area of rectangle

= length ×breadth

= 45 ×60

= 2700

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

step-by-step explanation:

b and c