a        A triangle ABC is right angled at B and has base AB of length 6, height BC of length 8 and hypotenuse AC of length 10. N is a point on BC such that line AN bisects angle BAC. What is the distance BN?

b       A triangle ABC is right angled at B and has base AB of length x, height BC of length y and hypotenuse AC of length h, so h² = x² + y². N is a point on BC such that line AN bisects angle BAC. What is the distance BN, in terms of x, y and h?