Question

The value of a for which the angle between and and the angle between and z-axis is 7- 27o is obtuse acute and less than is​

Answer 1

Answer:

Let a =2x 2i^ +4x j^ + k^ and b =7 −2 j^ +x k^

.

The angle between

a and b is obtuse

⇒ a . b <0⇒14x −8x+x<0

⇒x(2x−1)<0

⇒x∈(0, 21