For #8, since this is an isosceles triangle, we know that the 2 angles with the x and y are equal. To find the number of degrees left in the triangle after accounting for the 98 degrees, we do 180 - 98 = 82 degrees left. Since that will get split between two angles, there are 41 degrees in each angle.

So we set 5x + 6 = 41

5x = 45

x = 9

Also, y - 9 = 41

y = 50

9) Again the isosceles triangle tells us that:

6y - 5 = 10y - 41 (we can use this to solve for y).

-5 + 41 = 4y

36 = 4y

y = 9

Now, plug in y into one of the angles to get the number of degrees:

6(9) - 5 = 49 degrees

Each of the 2 angles with y's are 49 degrees. The number of degrees left for the third angle is: 180-(49+49) = 180 - 98 = 82

Set 12x + 22 = 82

12x = 60

x = 5

10) The isosceles triangle tells us that the sides 2x - 1 and x + 4 are equal:

2x - 1 = x + 4

x = 1 + 4 = 5

Plug x into one of the sides:

2(5) - 1 = 9

The perimeter would be 9 + 9 + 7 = 25

Dec 2nd, 2014

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