Question

Angle between the rays with d.r.'s 4, – 3, 5 & 3, 4, 5 is-

• A. cos–1$\sqrt { \frac { 4 } { 6 } }$
• B. cos–1$\left( \frac { 2 } { 6 } \right)$
• C. cos–1 $\left( \frac { 1 } { 2 } \right)$
• D. Not defined

Answer 1

Answer: (C)

cos–1 $\left( \frac { 1 } { 2 } \right)$

Answer 2

cos q =

=$\frac { 12 - 12 + 25 } { \sqrt { 16 + 9 + 25 } \cdot \sqrt { 9 + 16 + 25 } }$ = $\frac { 1 } { 2 }$

q = cos–1$\left( \frac { 1 } { 2 } \right)$