Question 289565
Hello, 
Since we know the Area of a triangle is equal to 1/2(Base times height) we can plug in the values known and let "x" represent the height:
100=1/2(x)(2x) Rewritten as:
100=x^2
Square root each side to get:
x=10
So height is 10 km
Width is 20 km
Make sense?
There's a book I wrote that might help;
www.math-unlock.com