All body movements occur in different planes and around different axes. A plane is an imaginary flat surface running through the body. An axis is an imaginary line at right angles to the plane ...

x - 7\). If the lines are parallel then \({m_1} = {m_2}\) and if \({m_1} = {m_2}\) then the lines are parallel. The gradient of a line which is parallel to the \(y\)-axis cannot be determined from ...