Answer:
10 mm
Explanation:
We know that the formula for a triangle is A= 1/2(b)(h)
Plug in 30mm for the area as shown and 6 for the base= 30=1/2(6)(h)
Solve= 30=3h
Divide each side by 3 to get h by itself. h=10 or b= 10
depends on which one is missing ^^