All the dimensions of a triangle were multiplied by the same factor. If the base of the triangle went from 1 centimeter to 3 centimeters, the are of the triangle was multiplied by

Nine

Three

Twelve

Six

The area is multiplied by 9.

let x be the base

let y be the height

since all dimensions were multiplied by the same number, 3,

original area,

1/2 * x * y = (1/2) xy

New area,

1/2 * 3x * 3y = (1/2) (9) xy

hence, area is multiplied 9 times.

the area of the triangle was multiplied by 9