Given that DE || BC, AD : DB = 3 : 4, find out ar(∆ADE)/ar(∆ABC)?

If angle bisector of a triangle bisects the opposite side, then what type of triangle is it?

Each interior angle of a regular polygon is 144⁰. The number of sides of the polygon is 

In triangle ABC, F is the centroid. If AB=11 cm, BC=14 cm and AC=7 cm, then what is the value (in cm) of EF?

In ∆ABC, AC = BC and ∠BAC = 40°. If BC is extended to D such that BC = CD, find out ∠ADC = ?

A field in the shape of a trapezium whose parallel sides are 200 meter and 400-meter-long, whereas each of other two sides is 260 meter long. What is the area (in m²) of the field?

AD is the median of a triangle ABC and O is the centroid such that AO = 10 cm. The length of OD (in cm) is 

Each internal angle of regular polygon is two times its external angle. Then the number of sides of the polygon is: