1. K

    Cryptography (Hill + Playfair) For anyone who loves a challenge, I need some brains

    Hello, I have been given a message encrypted with the hill cipher using a 2x2 matrix and have to try and recover both the plaintext and the matrix used. If anyone could help me at all with this I would be very grateful as I haven't succeeded in returning any of the plaintext so far and have...
  2. E

    Everone loves a cirlce(Worried)

    The equation of a cirlce is (x+1)(squared) + y(squared)=13 i)Write down the centre and radius of this cirlce ii)find the equation of the tangent to this cirlce at the point (2,2) Thank you