Question

The angle between the planes $3 x - 4 y + 5 z = 0$ and

$2 x - y - 2 z = 5$ is

• A. $\frac { \pi } { 3 }$
• B. $\frac { \pi } { 2 }$
• C. $\frac { \pi } { 6 }$
• D. None of these

Answer 1

Answer: (B)

$\frac { \pi } { 2 }$

Answer 2

$\theta = \cos ^ { - 1 } \left[ \frac { 6 + 4 - 10 } { \sqrt { 50 } \sqrt { 9 } } \right] = \cos ^ { - 1 } ( 0 ) = \frac { \pi } { 2 }$.