Question

The sides of an equilateral triangle are (2a - b)cm, (a + 3b) cm and (2a - 2b + 1) cm then the perimeter of the triangle is

• A. 3 cm
• B. 12 cm
• C. 15 cm
• D. 21 cm

Answer 1

The correct option is D 21 cm

The sides of equilateral triangle is (2a-b),(a+3b) and (2a-2b+1)

Then (2a-b)=(1+3b) = (2a-2b+1)

If 2a-b=2a-2b+1

Then -b+2b=1 or b=1

If 2a-b=a+3b (put the value of b=1

Then 2a-a=1+3 or a=4

Then perimeter of equilateral triangle=2a-b+a+3b+2a-2b+1=8-1+4+3+8-2+1=21 cm