Find the value of `'lambda'` if the planes `vecr. (hati +2hatj+3hatk)+3=0` and `vecr. (lambdahati+2hatj+7hatk) = 10` are perpendicular.

Explanation

Here `vecn_(1) = hati+2hatj+3hatk`
and `vecn_(2) = lambdahati+2hatj-7hatk`
For perpendicular planes
` vecn_(1).vecn_(2) = 0`
`rArr (hati+2hatj+3hatk).(lambdahati+2hatj-7hatk)=0`
`rArr lambda +4 - 21 = 0`
`rArr lambda = 17`.