Answer:
b1 = 9 cm
Step-by-step explanation:
The formula for area of a trapezoid is
A = 1/2 (b1+b2) *h
We know Area = 135 CM ^2, Height = 10 CM, b2 = 18 cm
Substituting these in
135 = 1/2 (b1+18) *10
Multiply 1/2*10
135 = 5 (b1+18)
Divide both side by 5
135/5 = 5/5 (b1+18)
27 = b1+18
Subtract 18 from each side
27-18 = b1+18-18
9 = b1
This is an equilateral triangle of height a√3/2 where a is the side length. So the area is ½a.a√3/2=a²√3/4.
So a²=25 and a=5cm. Therefore the perimeter is 3a=15cm.
A nice graphing utility can be found at the link below, along with your graph and the corresponding table of values.
https://www.desmos.com/calculator/qe8pnxwqdb
The reason that 9.6 is rational is because it can be turned into a fraction.
The fraction is 48/5.
Rational numbers are numbers that can be turned into a fraction, while irrational numbers a those who cannot be turned into a fraction.
Probability is calculated by comparing the odds to a certain event occurring to the number of possible events.
P=

For example, take a six-sided dice number 1-6 on each side. The probability of rolling a 4 would be1 in 6 or 1/6. This is because of the six possible outcomes, rolling a 4 is only one of them.
P(4)=1/6
Now take the same dice. The probability of rolling an even number is 3/6. To see why, lets look at the total possible outcomes:
1
23
45
6
Of the 6 possibilities, 3 are even numbers.
P(even)=3/6 or 1/2