NDA2019MathematicsThree Dimensional GeometryActual

What are the direction cosines of z -axis?

Options

A1,1,1
B1,0,0
C0,1,0
D0,0,1

Correct answer

D. 0,0,1

Step-by-step solution

Z makes an angle 90° with the x-axis 90° with the y-axis at 0° with the z-axis. Therefore; α is equal to 90 degree, β is equal to 90 degree and γ is equal to 0 degrees. Therefore l is equal to 0, m is equal to 0 and n is equal to 1 and the direction cosine of the z-axis is 0,0,1

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