Answer:
Question 4: -11
Question 5: -7
Step-by-step explanation:
Four
Every triangle has 180 degrees.
So all three angles add to 180
<em><u>Equation</u></em>
60 + 80 + x + 51 = 180
<em><u>Solution</u></em>
Combine the like terms on the left. This is the first time I've seen x be a negative value. Almost all of the time it isn't, which should make you wonder.
191 + x = 180
Subtract 191 from both sides.
191 - 191 + x = 180 - 191
x = - 11
Five
If a triangle is a right triangle and one of the angles is 45, then so is the other one.
<em><u>Proof</u></em>
a + 45 + 90 = 180 Combine like terms on the left
a + 135 = 180 Subtract 135 on both sides.
a + 135-135=180-135 Combine the like terms
a = 45
<em><u>Statement</u></em>
That means 52 + x = 45 and here is another negative answer. Subtract 52 from both sides
52 - 52 + x = 45 - 52 Combine like terms.
x = - 7
C is on the line and D is not on the line.
-1/2(-40)+1=21
-1/2(20)+1≠-11
