Question

Choose correct alternatives :

The angle between the planes `bar"r".(hat"i" - 2hat"j" + 3hat"k") + 4 = 0 and bar"r".(2hat"i" + hat"j" - 3hat"k") + 7 = 0` is

विकल्प

• `pi/(2)`

• `pi/(3)`

• `cos^-1(3/4)`

• `cos^-1(9/14)`

Answer 1

`cos^-1(9/14)`