If in ΔABC, DE ||BC, AB = 7.5cm, BD = 6cm and DE = 2cm, then the length of BC in cm is :

If 9x² + 16y² = 60  and 3x + 4y = 6, then the value of xy is

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If x = √2+1, then the value of x4-1/x4 is

A can do a work in 12 days while B can do it in 15 days. They undertake to complete it together for Rs. 450. what will be the share of A in this amount of money 

If x = a cosθ+ b sinθ and y = b cosθ- a sinθ, then x2 + y2 is equal to

An angle in a semicircle is