ΔABC is an equilateral triangle in which D, E and F are the points on sides BC, AC and AB, respectively, such that AD ⊥ BC, BE ⊥ AC and CF ⊥ AB. Which of the following is true?

In the figure below, find the value of AB.

In the triangle ABC, AB = 2 cm, BC = 3 cm and AC = 4 cm. D is the middle point of AC. If a square is constructed on the side BC, what is the area of the square?

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

If diagonals of a rhombus are 16 cm and 30 cm. then what is the perimeter (in cm) of the rhombus?

Given that (a²+b²)=60, then find the value of (a+b)²+(a–b)².

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 

If the perimeter of a rhombus is 80 cm and one of its diagonals is 24 cm, then what is the are (in cm²) of the rhombus?