All layers are incredibly important. If we didn't, we would die very quickly and life would be inhabitable. The radiation from the son would kill us. The heat from the sun would dry up water and kill crops leaving us with no food/water.
An Isosceles triangle has two even parts, you add them up. For example 60 degree plus another 60 degree angle is 120 degrees. And the limit is 180 degrees, so in order to get that last angle, you'd have to subtract 160 from 180. And that'd be 20 degrees. I couldn't see the question but I hope this helps you in a way
The correct answer is steppes. I hope this helps.