જો $\vec{a},\vec{b},\vec{c}$ એ ત્રણ શૂન્યેતર અસમતલીય સદિશો છે અને are three non-zero, non-coplanar vectrors and $\overrightarrow {{b_1}} \, = \,\overrightarrow {b\,} \, - \,\frac{{\overrightarrow b \,.\,\overrightarrow a }}{{{{\left| {\overrightarrow a \,} \right|}^2}}}\overrightarrow a \,,\,\overrightarrow {{b_2}} \, = \overrightarrow b \, + \,\frac{{\overrightarrow b \,.\,\overrightarrow a }}{{{{\left| {\overrightarrow a \,} \right|}^2}}}\overrightarrow a \, $ and $ \overrightarrow {{c_1}} \, = \,\overrightarrow c \, - \,\frac{{\overrightarrow c \,.\,\overrightarrow a }}{{{{\left| {\overrightarrow a \,} \right|}^2}}}\overrightarrow a \, + \,\frac{{\overrightarrow c \,.\,\overrightarrow b }}{{{{\left| {\overrightarrow b \,} \right|}^2}}}\overrightarrow {{b_1}} \, $, $\overrightarrow {{c_2}} \, = \,\overrightarrow c \, - \,\frac{{\overrightarrow c \,.\,\overrightarrow a }}{{{{\left| {\overrightarrow a \,} \right|}^2}}}\overrightarrow a \, - \,\frac{{\overrightarrow c \,.\,\overrightarrow b }}{{{{\left| {\overrightarrow {{b_1}} \,} \right|}^2}}}\overrightarrow {{b_1}} \, ,$ $ \overrightarrow {{c_3}} \, = \,\overrightarrow c \, - \,\frac{{\overrightarrow c \,.\,\overrightarrow a }}{{{{\left| {\overrightarrow c \,} \right|}^2}}}\overrightarrow a \, + \,\frac{{\overrightarrow c \,.\,\overrightarrow {{b_2}} }}{{{{\left| {\overrightarrow c \,} \right|}^2}}}\overrightarrow {{b_1}} \, $ $, \overrightarrow {{c_4}} \, = \,\overrightarrow c \, - \,\frac{{\overrightarrow c \,.\,\overrightarrow a }}{{{{\left| {\overrightarrow c \,} \right|}^2}}}\overrightarrow a \, - \,\frac{{\overrightarrow b \,.\,\overrightarrow c }}{{{{\left| {\overrightarrow b \,} \right|}^2}}}\overrightarrow {{b_1}} \,.$ હોય તો નીચેનામાંથી ક્યુ પરસ્પર લંબ સદિશોનો ગણ છે.
→જો $f(x) = \left\{ \begin{array}{l}\,\,\,\,\,\,\,\,\, - {x^2},\,{\rm{when\,\, }}x \le 0\\\,\,\,\,\,5x - 4,\,{\rm{when\,\,}}0 < x \le 1\\4{x^2} - 3x,\,{\rm{when \,\,}}1 < x < 2\\\,\,\,\,\,3x + 4,{\rm{when\,\, }}x \ge 2\end{array} \right.$ તો
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