If the angle of elevation of a cloud from a point 200 m above a lake is 30o and the angle of depression of its reflection in the lake is 60o. Then the height of the cloud above the lake is

If tan 3 θ, tan 7 θ = 1, then the value of tan(θ+36⁰) is

Radius of the incircle of an equilateral ΔABC of sides 2√3 units is x cm. The value of x is

The circum-centre of a triangle ABC is O. If ∠BAC = 85o, ∠BCA = 75o, then ∠OAC is of

If a2 + 13b2 + c2 - 4ab - 6bc = 0, then a:b:c is

If x² - xy + y² =2 and x⁴ + x²y² + y⁴ = 6, then the value of x² + xy + y² is: