In Fig. 4.243, the value of x for which is
Given in ΔABC, DE || AB.
We know that basic proportionality theorem states that if a line is drawn parallel to one side of a triangle to intersect the other two sides in distinct points, then the other two sides are divided in the same ratio.
Then
⇒ (x + 3) (3x + 4) = x (3x + 19)
⇒ 3x2 + 4x + 9x + 12 = 3x2 + 19x
⇒ 19x – 13x = 12
⇒ 6x = 12
∴ x = 2 cm