Which of the following equation is correct for the new X co-ordinate if an object undergoes 3D rotation around z axis? a) Xnew = Xold x cosθ – Yold x sinθ b) Xnew = Xold x cosθ + Yold x sinθ c) Xnew = Xold x sinθ – Yold x cosθ d) Xnew = Xold x sinθ + Yold x cosθ
Answer: a Explanation: The correct equation for the new X co-ordinate if an object undergoes 3D rotation around z axis is – Xnew = Xold x cosθ – Yold x sinθ When the matrix form for 3D rotation around z axis is expanded then we get the following equations – Xnew = Xold x cosθ – Yold x sinθ; Ynew = Xold x sinθ + Yold x cosθ; Znew = Zold
