19. If the triangle below is equilateral, write an expression using parentheses to show the
perimeter of the triangle. Then, give the
simplified expression.
4x - 3

Perimeter of the triangle = (12x - 9)

Step-by-step explanation:

Property of an equilateral triangle:

- All sides are equal in measure.

- All interior angles are equal.

Since, measure of one side of the triangle = (4x - 3)

And perimeter of a polygon = Sum of all sides of the polygon

Therefore, perimeter of the given triangle = (4x - 3) + (4x - 3) + (4x - 3)

                                                                      = (4x + 4x + 4x) - (3 + 3 + 3)

                                                                      = (12x - 9)

Perimeter of the triangle = (12x - 9)

12cm

the answer is d