Suppose $\overline{\mathrm{a}}=\mathrm{\lambda }\overline{\mathrm{i}}-7\overline{\mathrm{j}}+3\overline{\mathrm{k}},\overline{\mathrm{b}}=\mathrm{\lambda }\overline{\mathrm{i}}+\overline{\mathrm{j}}+2\mathrm{\lambda }\overline{\mathrm{k}},$ If the angle between $\overline{\mathrm{a}}\text{ and }\overline{\mathrm{b}}$  is greater than 90°, then $\mathrm{\lambda }$satisfies the inequality.