Answer:
Given: and
.
Prove:
Since , By the definition of perpendicular lines angles 1, 2, 3 and 4 are 90 degree. similarly
, it means angles 5, 6, 7 and 8 are 90 degree.
We can say that,
,
,
and
From figure it is noticed that the angle 1 and 5 are corresponding angles.
If two parallel lines are intersected by a transversal, then the corresponding angles are equal.
Since corresponding angles are congruent, therefore the line must be parallel to each other.
Hence proved that .
You only flip the inequality sign when you multiply or divide both sides by a negative number.
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Problem 1
The inequality sign flip happens because we divided both sides by -8.
The graph will have a closed circle at 4 with shading to the left.
Three solutions are x = 0, x = 1, x = 2. You can pick any three numbers you want as long as they are 4 or smaller.
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Problem 2
The graph will have an open circle at 13/3 = 4&1/3 = 4.333 approx. The shading is to the left. No inequality sign flip happens because we divided both sides by a positive number.
Your choice of three solutions is correct. You can pick anything smaller than 4.3333
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Problem 3
The solution set is any value 3 or larger. Three solutions are x = 5, x = 6 and x = 7.
The graph has a closed circle at 3 on the number line. The shading is to the right.