The angle between the lines `(x^(2)+y^(2))sin^(2)alpha=(x cos beta-y sin beta)^(2)` is

The angle between the pair of lines (x^(2)+y^(2))sin^(2)alpha=(x cos theta-y sin theta)^(2);is

The angle between the lines x cos alpha+y sin alpha=p_(1) and x cos beta+y sin beta=p_(2) when alpha>beta

The angle between lines x cos alpha+y sin alpha=p_(1), and x cos beta+y sin beta=p_(2), where alpha>beta is

The angle between the lines x cos alpha+y sin alpha=a and x sin beta-y cos beta=a is (i)beta-alpha(ii)pi-alpha-beta(iii)(pi)/(2)-beta-alpha(iv)(pi)/(2)-

The lines x cos alpha+y sin alpha=P_(1) and x cos beta+y sin beta=P_(2) will be perpendicular,if :

If cos alpha, cos beta, cos gamma are the direction cosines of a line then the value of sin^(2) alpha + sin^(2) beta + sin^(2) gamma is__________