Answer:
Explanation:
In an elliptical orbit , the angular momentum of the planet remains constant because velocity of planet makes a right angle to the direction to the star .
mvr = constant .
mv₁r₁ = mv₂r₂
v₁r₁ = v₂r₂
v₁ x 21 = 38 x 75
v₁ = 135.71 km/s .