Angles (1) and (3) are vertical angles (the pair of angles that are directly across from each other when two straight lines intersect), therefore equal. Equate angles (1) and (3):
6y + 29 = 12y - 7 -->
6y -12y = -7 - 29 -->
-6y = -36 -->
y = 6
Likewise, angles (2) and (4) are equal. Therefore equate:
4x + 31 = 6x - 11 -->
4x - 6x = -11 -31 -->
-2x = -42 -->
x = 21
Verification: Plug x=21, y=6 in the measures and calculate each angle. Then add; they should add up to 360 degrees:
M1 = 6*6 + 29 = 36 + 29 = 65
M2 = 4*21 + 31 = 84 + 31 = 115
M3 = 12*6 - 7 = 72 - 7 = 65 (equals angle M1)
M4 = 6*21 - 11 = 126 - 11 = 115 (equals angle M2)
Add: 65+115+65+115 = 360
2007-09-27 06:22:16
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answer #1
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answered by Anthony P - Greece 2
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When two lines intersect to form 4 angles and if the angles are measured 1, 2, 3, 4 clockwise, then
m<1 = m<3
m<2 = m<4
because they are pairs of opposite angles.
so
6y + 29 = 12y - 7
subtract 6y
29 = 6y - 7
add 7
36 = 6y
y = 36/6 = 6
m<1 = m<3 = 6(6) + 29 = 36+29 = 65 degrees
similarly
4x + 31 = 6x - 11
2x = 42
x = 21
m<2 = m<4 = 4x+31 = 4(21) +31 = 84 + 31 = 115 degrees
note: sum of all the angles(1,2,3,4) should add up to 360
because they form full circle. here 2(65 + 115) = 2(180) = 360
and (1+2) = (3+ 4) = 180 because they form linear pair
2007-09-27 06:30:56
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answer #2
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answered by mohanrao d 7
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Unfortunately, your question is not entirely clear, especially without the accompanying diagram, but from what I understand, two lines cut each other and make four angles, correct? Now, since the opposite angles would be equal in this case, the measures of angles 1 and 3 (and 2 and 4) would be the same. So, putting this information in an equation gives us:
6y+29 = 12y-7
6y = 36
y = 6
Which gives the measure of angle 1 (and that of 3) to be 65 degrees (by substituting the value for y).
If you want to also find the value of x and the measures of angles 2 and 4, remember that adding up angles 1 and 2 (and 3 and 4) would give us 180 degrees, and since angle 1 is 65 degrees, this makes the measure of angle 2 to be 115 degrees, and then use this information to solve for x.
2007-09-27 06:24:13
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answer #3
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answered by pyaarmusafir 2
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Vertical angles are equal so angle 1 = angle 3 and angle 2 = angle 4.
So 6y+29 = 12y-7
6y =36
y = 6
So angle 1 = angle 3 = 65 degrees
4x+31=6x-11
2x = 42
x =21
So angle 2=angle 4 = 115 degrees
This checks because angle 1 + angle 2 = 115+65 = 180 = a straight line.
2007-09-27 06:19:21
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answer #4
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answered by ironduke8159 7
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Angles (1, 2) (2,3) (3,4) and (4,1) are supplementary, meaning they form a line together. And because of that, they add up to 180 degrees (measure of a line).
(6y+29) + (4x+31) = 180
(12y-7) + (6x-11) = 180
You now have 2 equations and 2 unknowns to solve for.
Edit: You're thinking of Vertical Angles, Endo.
2007-09-27 06:17:32
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answer #5
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answered by np_rt 4
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To solve this problem you must first recognize that angles 1 & 3 and 2 & 4 are equal. (For the life of me I cannot remember the name of this identity!) Once you recognize that you can set the x functions and the y functions equal to each other.
4x + 31 = 6x-11
6y + 29 = 12y - 7 (That is supposed to be 12y, right?)
No just solve for x and y:
x = 21
y = 6
2007-09-27 06:17:03
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answer #6
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answered by endo_jo 4
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when two lines cross each other, the vertically opposite angles are equal. so
M of angle1=M of angle 3
6y+29=12y-7
6y=36
y=6. ANS.
M of angle 1 =6*6+29=65degrees
=65degrees. ANS.
Excellent father!
measureof angle 3 is also 7degrees
2007-09-27 06:24:57
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answer #7
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answered by Anonymous
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opposing angles will be equal. so <1 and <3 are equal
and <2 and <4 are equal.
set equations to each other and solve.
2007-09-27 06:18:39
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answer #8
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answered by Kenneth H 3
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The answer is 42.
2007-09-27 06:23:54
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answer #9
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answered by Anonymous
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