(1)Given two vectors , a and b where a and b are both not 0 , show that if |a+b|=|a-b| , then a and b are perpendicular to each other .

(2) if a and b are perpendicular to each other , show that

|a+b|=|a-b|=$\displaystyle \sqrt{|a|^2+|b|^2}$