Answer: 126 mm^2 - C
Step-by-step explanation: Hello! The formula for area of a triangle is 1/2(b)(h). b = base and h = height. You would multiply the base and height by 1/2 because a triangle is 1/2 the size of a square. The formula for the area of a square is (b)(h), and you would have to multiply (b)(h) to find the area of a triangle with the same base and height. The base of this triangle is 28 mm, and the height of this triangle is 9 mm. Substitute 28 mm in for the base, and 9 mm in for the height. (28)x(9) = 252. Now you have to multiply 252 x 1/2. 252 x 1/2 = 126. The answer is C, 126.