Answer:

Step-by-step explanation:
Given:

1.

2.

3.

4.

5.

6.

7.

8.

For Commutative Property of Addition
Let us take a decimal number
and a fraction 
Now, according to the Commutative property of Addition:
For any two numbers
and
:

So, for
and 
Let us add


Also,


Therefore, 
Hence, Commutative Property of Addition is satisfied.
For Associated Property of Addition
Let us take two same decimal numbers
,
and a fraction 
Now, according to the Associated property of Addition:
For any three numbers
,
and 

So, for
,
and 
The Left hand side:







The Right hand side:






Thus,

Therefore, 
Hence, Associative Property of Addition is satisfied.
Answer:
Step-by-step explanation:
Comment
The way the diagram looks when it is drawn is that you are going to need the sine function to solve for the side opposite which is CD.
Formula
Sin(A) = Sin(68 = opposite / hypotenuse Substitute values.
Solution
sin(68) = altitude (side opposite) / 20 multiply both sides by 20
20*sin(68) = 20* altitude / 20 substitute for sin(68)
20* 0.9272 = altitude
altitude = 18.5
Answer: 18.5 to the nearest tenth
If I were solving this equation, I would put x^2-20x+(100)=(10). Since this is in standard form, you could change this into vertex form by making the equation y=(x-10)^2 -10.