exercise2.hs

diff :: Int -> Int -> Int
diff x y = abs (x-y)

triangleArea :: Float -> Float -> Float -> Float
triangleArea a b c =
             let s =(a + b + c) / 2
             in sqrt(s*(s-a)*(s-b)*(s-c))

isSum :: Int -> Int -> Int -> Bool
isSum a b c =
            if ( a + b == c || a + c == b ||  b + c == a )
                then True
                    else False

ex3 :: Float -> Float -> Float -> Float
ex3 a b c =
        if ( a + b < c || a + c < b ||  b + c < a )
            then error "Idiot alert, not a triangle"
                else
                    let s =(a + b + c) / 2
                    in sqrt(s*(s-a)*(s-b)*(s-c))