In the figure given below ABC is an equilateral triangle of side 6√3 cm and AD is the median of the triangle from point A and G is the centroid of the triangle. If DP = 4 cm, then what is the length of GP?
In the figure given below ABC is an equilateral triangle of side 6√3 cm and AD is the median of the triangle from point A and G is the centroid of the triangle. If DP = 4 cm, then what is the length of GP? Correct Answer 5 cm
GIVEN:
AB = BC = CA = 6√3 cm and AD is the median of the triangle and G is the centroid of the triangle. DP = 4 cm.
CONCEPT:
In equilateral triangle, all the centers (Incentre, circumcenter, orthocenter, centroid) lie at the same point, so median AD will be perpendicular to BC and it will bisect BC too.
Centroid divides the median in the ratio 2 : 1.
CALCULATION:
Now,
BD = 6√3 / 2 = 3√3 cm
Since, in equilateral triangle, all the centers lie at the same point. So, AD is perpendicular to BC.
In ∆ABD,
AB2 = BD2 + AD2
⇒ (6√3)2 = (3√3)2 + AD2
⇒ AD = 9 cm
⇒ GD = 9 × (1 / 3) = 3 cm
In ∆GDP:
GP2 = GD2 + DP2
⇒ GP2 = 32 + 42
∴ GP = 5 cm