Inverse kinematics

[Mahmoud]

 
what is the the inverse kinematics of a robot whose forward kinematics is
x= L1*cos(theta1)+L2*cos(theta1+theta2)
y=L1*sin(theta1)+L2*sin(theta1+theta2)+d
where d is the distance that the whole robot arm can move up or down
I mean there is a prismatic joint in the shoulder of the robot arm
so we need to find d, theta1 and theta2