OCR Further Additional Pure 2022 June — Question 5

Exam BoardOCR
ModuleFurther Additional Pure (Further Additional Pure)
Year2022
SessionJune
TopicVector Product and Surfaces

5 You are given the variable point \(A ( 3 , - 8 , t )\), where \(t\) is a real parameter, and the fixed point \(B ( 1,2 , - 2 )\).
  1. Using only the geometrical properties of the vector product, explain why the statement " \(\overrightarrow { \mathrm { OA } } \times \overrightarrow { \mathrm { OB } } = \mathbf { 0 }\) " is false for all values of \(t\).
    1. Use the vector product to find an expression, in terms of \(t\), for the area of triangle \(O A B\).
    2. Hence determine the value of \(t\) for which the area of triangle \(O A B\) is a minimum.