Find the measure of ∠feg. a) 25° b) 65° c) 80° d) 90°

First, you have to set 5x equal to (3x+10). They are vertical angles and therefore congruent.

5x = 3x+10              The variable should only be on one side of the equation,

5x - 3x = 10             Therefore subtract 3x from both sides

2x = 10                     Divide by 2 on both sides.

x = 5

We're not done yet, since we've found the x-value we have to solve for ∠GEC.

∠GEC = 3x+10 = 3(5)+10 = 15+10 = 25°

∠GEC and ∠FEG form a right angle. This means that the sum of the two angles is 90°

90° = 25° + x            In this case, we're using "x" to solve for ∠FEG

90-25 = x                  We subtract 25 from both sides to get the variable by itself.

65° = x

let's cover over the formula of the vertex:

y = a(x – h)^2 + k

in this formula, (h,k) are the vertex, always remember that the positive or negative value of the vertex is based on the sign it has.

for example, if the vertex is -3,-6 then both the x and y value would have the positive sign attached to it and if it were a positive x and y value, then a negative sign would be attached to it.

with that being said, for our problem the x value is a positive one so we are looking for a number with a negative sign next to it, in this case the first and second choice.

however, for the first answer choice it isn't quite part of the formula so we know that the answer choice correctly displays the x value.

to confirm, we can see if the -1 fits correctly with the second answer choice, and as mentioned above a negative number will have a positive sign attached to it. so, for our problem we can see that -1 has been changed to +1, so we can confirm that the second answer choice is correct.

hence, our final answer is y=(x - 1)^2 + 1