Question

The length of a side of an equilateral triangle is (-2xy+10xy) units, where x = -1 and y = -2. Find its perimeter. ​

Answer 1

Answer:

Step-by-step explanation:

As all the sides of an equilateral triangle are equal, 2x−3y+1=x+y−1 and x+y−1=3x−y−9. Hence

x−4y=−2,...…..(1)

2x−2y=8...…..(2)

Multiplying (2) by 2 and subtracting (1) from it, we get 3x=18. Hence x=6.

Finally 2y=2x−8=2(6)−8=12−8=4. Hence y=2.

Thus the side of the triangle is x+y−1=6+2−1=7cm. Its perimeter is 3×7=21 cm.