Riddle Me This

[isaysroar]

Since no one managed to find an answer let's start a new one. Also, whoever started the barn riddle please post the answer.
Here's the new riddle:

A farmer challenges an engineer, a physicist, and a mathematician to fence off the largest amount of area using the least amount of fence.

The engineer made his fence in a circle and said it was the most efficient.

The physicist made a long line and said that the length was infinite. Then he said that fencing half of the Earth was the best.

The mathematician laughed at the others and with his design, beat the others. What did he do?

[mrburrito]

He didn't fence off anything.

What has four legs in the morning, two legs during the day, and none at night?

[Cedavis6]

He didn't fence off anything.

What has four legs in the morning, two legs during the day, and none at night?

Man.

[iwonder]

Got another riddle?

[isaysroar]

He didn't fence off anything.

What has four legs in the morning, two legs during the day, and none at night?

He didn't fence off anything.

What has four legs in the morning, two legs during the day, and none at night?

Man.

Actually... You both got it wrong. The mathematician HAS to use fencing.

[ScienceOlympian]

Since no one managed to find an answer let's start a new one. Also, whoever started the barn riddle please post the answer.
Here's the new riddle:

A farmer challenges an engineer, a physicist, and a mathematician to fence off the largest amount of area using the least amount of fence.

The engineer made his fence in a circle and said it was the most efficient.

The physicist made a long line and said that the length was infinite. Then he said that fencing half of the Earth was the best.

The mathematician laughed at the others and with his design, beat the others. What did he do?

The mathematician made a fence around himself and then told the others that he was on the outside of the fence.

[isaysroar]

Since no one managed to find an answer let's start a new one. Also, whoever started the barn riddle please post the answer.
Here's the new riddle:

A farmer challenges an engineer, a physicist, and a mathematician to fence off the largest amount of area using the least amount of fence.

The engineer made his fence in a circle and said it was the most efficient.

The physicist made a long line and said that the length was infinite. Then he said that fencing half of the Earth was the best.

The mathematician laughed at the others and with his design, beat the others. What did he do?

The mathematician made a fence around himself and then told the others that he was on the outside of the fence.

YUP!

[ScienceOlympian]

What's the difference between a viola and a trampoline?
(Not to offend any violists- I am a violist, too, but I LOVE viola jokes.

[ScienceOlympian]

What's the difference between a viola and a trampoline?
(Not to offend any violists- I am a violist, too, but I LOVE viola jokes.

[Epicness101]

I'm a violinist, but my teacher is a violist by trade, so here's the answer: You take your shoes off to jump on the viola. Am I somewhere close?

Here's the riddle in advance. If I got the above riddle correct, answer this, if not then scratch what's below.

Timmy and Tammy were born on the same day, same year, same month. They hopped out of their mother's womb two minutes apart. Yet the were not twins, why is that?