Final answer:
If the dimensions of a triangle with a base of 4m and height of 5m are multiplied by 3, the area is affected by becoming 90m².
Step-by-step explanation:
The area of a triangle is calculated using the formula: Area = 1/2 * base * height.
If the base of a triangle is multiplied by 3, the new base becomes 4m * 3 = 12m. If the height is also multiplied by 3, the new height becomes 5m * 3 = 15m.
Using the new dimensions of the triangle (base = 12m, height = 15m), we can calculate the new area: New Area = 1/2 * 12m * 15m = 90m².