If the major axis of an ellipse is 16 cm, what is the semimajor axis? if the eccentricity is 0.8, would this ellipse be best described as mostly circular or very elongated?

Semi major axis: 8 cm.

The ellipse will be elongated.

Explanation:

Remember that the exccentricity of an elipsis is calculated by dividing the distance from the center to the foci by the distance from the center to the vertices, the closer that ratio is to one the more elongated the ellipse will be, and the closest it is to zero the most circular it will be, in this case the eccentricity is .8 so it would be very elongated.

The semi major axis is always half the major axis of the ellipse so 16/2=8, the semi major axis would be 8.

diagram is missing, but i will try to explain your doubt.

answer:

amplitude is the maximum displacement or distance moved on a point of a vibrating body or wave measured from its equilibrium position.it is equal to half the length of vibration path.