Question 447176
Let the base = x m, then the height will be: x-5 m. Since the are is 42 m, substituting in the area formula{{{A=b*h/2}}} we get:

{{{42=x(x-5)/2}}}, set the equation to zero:{{{x^2-5x-84=0}}}, solving the equation find {{{x=12 m}}}

Answer:The base of triangle is 12 m.