If `cos^(-1)lambda+cos^(-1)mu+cos^(-1)gamma=3pi,` then find the value of `lambdamu+mulambdadot`

Explanation

We know that `0 le cos^(-1) x le pi`
Hence, from the equation
`cos^(-1) lamda = pi, cos^(-1) mu = pi, cos^(-1) gamma = pi`
[`:' cos^(-1) lamda + cos^(-1) mu + cos^(-1) gamma = 3 pi` is possible only when each term attains its maximum]
`rArr lamda = mu = gamma = -1`
`rArr lamda mu + mu gamma + gamma lamda = 3`