Answer:
the median is 80.5
Step-by-step explanation:
first we put them in order
75,76,77,79,80,81,85,86,90,91
the median is the middle number...however, in cases where there are an even number of numbers, ur gonna have 2 middle numbers....so u take the average of those 2 numbers...basically, u add them and divide by 2.
So we have 2 numbers in the middle.....we add them and divide by 2 to get the median.
(80 + 81) / 2 = 161/2 = 80.5 <== the median
Any number to the power of 
is itself. So, 
.
Here are some more examples:
Given :
The diagonals of rhombus ABCD intersect at E.
∠CAD = 20°.
To Find :
The angle ∠CDA.
Solution :
We know, diagonals of a rhombus bisects each other perpendicularly.
So, ∠DEA = 90°.
In triangle ΔEAD :
∠EAD + ∠AED + ∠EDA = 180°
20° + 90° + ∠EDA = 180°
∠EDA = 70°
Now, we know diagonal of rhombus also bisect the angle between two sides .
So, ∠CDA = 2∠EDA
∠CDA = 2×70°
∠CDA =140°
Therefore, ∠CDA is 140°.
