Height ##=12 cm##
The area of a triangle can be determined with the equation ##
area = 1/2 * base * height##
Find the area of the first triangle, by substituting the measurements of the triangle into the equation.
##Areatriangle = 1/2 * 18*10##
## = 90cm^2##
Let the height of the second triangle ##=x##.
So the area equation for the second triangle ##=1/2*15*x##
Since the areas are equal,
##90 = 1/2 * 15*x##
Times both sides by 2.
##180 = 15x##
##x=12##