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