Given

Area of triangle = 50 m²

Let the length of the height of triangle be Y cm

Therefore its base is 4Y cm

Area of the triangle = × base × height = 50

× (4Y) × (Y) = 50

4Y² = 50 × 2 = 100

Y² = = 25

Y = 5 cm

Therefore length of base is 4 × 5 = 20 cm