Length of the sides of a triangle area a, b, c respectively. If a² + b² + c² = ab + bc + ca, then the triangle is

• Isosceles

• Equilateral

• Scalene

• Right-angled

Which of the set of three sides can't form a triangle?

• 5cm, 6cm, 7cm

• 5cm, 8cm, 15 cm

• 8cm, 15cm, 18cm

• 6cm, 7cm, 11cm

In a triangle ABC, if  and , then  is equal to

• 80°

• 40°

• 60°

• 20°

The point of intersection of all the three medians of a triangle is called its

• Orthocentre

• Incentre

• Centroid

• Circumcentre

In a triangle, the distance of the centroid from the three vertices is 4 cm, 6 cm and 8 cm respectively. Then the length of the smallest median is

• 8

• 7

• 6

• 5

X and Y are the mid-points of sides of AB and AC of Δ ABC. If BC + XY = 12 units, then BC - XY is:

• 8 units

• 4 units

• 6 units

• 2 units

77.

The length of the base of an isosceles triangle is 2x - 2y + 4z, and its perimeter is 4x - 2y + 6z. Then the length of each of the equal sides is:

• x + y

• x + y + z

• 2(x + y)

• x + z

In Δ PQR, L and M are two points on the sides PQ and PR respectively such that LM || QR. If PL = 2 cm, LQ = 6 cm and PM = 1.5 cm,  then MR in cm is

• 0.5

• 4.5

• 9

• 8

Δ ABC and Δ DEF are two similar triangles and the perimeter of ΔABC and ΔDEF are 30 cm and 18 cm respectively.  If length of DE = 36 cm, then the length of AB is

• 60 cm

• 40 cm

• 45 cm

• 50 cm

In Δ ABC, ∠B is right angle, D is the mid point of the side AC. If AB = 6 cm, BC = 8 cm, then the length of BD is

• 4 cm

• 5 cm

• 8 cm

• 12 cm