The expression \dfrac12bh 21 bhstart fraction, 1, divided by, 2, end fraction, b, h gives the area of a triangle where bbb is the base of the triangle and hhh is the height of the triangle. what is the area of a triangle with a base of 7 \text{ cm}7 cm7, space, c, m and a height of 4 \text{ cm}4 cm4, space, c, m? \text{ cm}^2 cm 2