Question 263227
Hello, 
Let's establish x to represent the base. We know the formula for the area of a triangle is: A=1/2BH So now let's plug in the values. 
9=1/2(x)(2x) Simplify this to be:
9=1/2(2x^2) The 1/2 and 2 turn to 1 so we have:
9=x^2 Square root both sides to get:
x=plus and minus 3  
Minus 3 doesn't work so it's 3 inches for the base. 
Got it?
RJ 
Check out a book I wrote at:
www.math-unlock.com