Final answer:
To find the new area of the triangle when the base and height are doubled, double the base length and height and use the formula for the area of a triangle.
Step-by-step explanation:
To find the new area of the triangle when the base and height are doubled, we need to calculate the new base and height and then use the formula for the area of a triangle.
Given that the base length is 3 centimeters and the area is 6 square centimeters:
Double the base length: 3 x 2 = 6 centimeters
Double the height: 6 x 2 = 12 centimeters
Calculate the new area: 1/2 x base x height = 1/2 x 6 x 12 = 36 square centimeters
Therefore, the new area of the similar figure is 36 square centimeters, so the correct answer is d) 24 square centimeters.