This is for question#30. You are right that the distance between A and D is 5, however what I marked in the figure is the distance from point D to the y-axis, which is 4 units. This would be the base of the resulting right triangle which has a height of 3 units. I hope this makes sense.

Sahil Kumar says

Shouldn’t the distance between A and D be 5?

Dabral says

Hi Sahil,

This is for question#30. You are right that the distance between A and D is 5, however what I marked in the figure is the distance from point D to the y-axis, which is 4 units. This would be the base of the resulting right triangle which has a height of 3 units. I hope this makes sense.

Dabral