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Use the diagram to find the measure of exterior angle BCD.

Triangle A B C has angles labeled as follows: A, (18x + 12) degrees; B, 6x degrees; C, unlabeled. Point C lies on Ray A D. The outside angle B C D is labeled (27x - 3) degrees.

left parenthesis 27 x minus 3 right parenthesis degrees(27x − 3)°

6 x degrees6x°

left parenthesis 18 x plus 12 right parenthesis degrees(18x + 12)°

DCAB

The measure of exterior angle BCD is ___

 

 
ladiikeiii  Dec 5, 2017

Best Answer 

 #1
avatar+5552 
+2

m∠BCA  +  m∠BCD   =   180

m∠BCA   =   180  -  m∠BCD

m∠BCA   =   180  -  (27x - 3)

 

the sum of the angles in a triangle  =  180°

6x  +  (18x + 12)  +  m∠BCA   =   180

6x  +  (18x + 12)  +  (180 - (27x - 3))   =   180

6x  +  18x - 27x + 12 + 180 + 3   =   180

-3x   =   -15

x   =   5

 

m∠BCD   =   (27x - 3)°

m∠BCD   =   (27(5) - 3)°

m∠BCD   =   132°

 
hectictar  Dec 5, 2017
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1+0 Answers

 #1
avatar+5552 
+2
Best Answer

m∠BCA  +  m∠BCD   =   180

m∠BCA   =   180  -  m∠BCD

m∠BCA   =   180  -  (27x - 3)

 

the sum of the angles in a triangle  =  180°

6x  +  (18x + 12)  +  m∠BCA   =   180

6x  +  (18x + 12)  +  (180 - (27x - 3))   =   180

6x  +  18x - 27x + 12 + 180 + 3   =   180

-3x   =   -15

x   =   5

 

m∠BCD   =   (27x - 3)°

m∠BCD   =   (27(5) - 3)°

m∠BCD   =   132°

 
hectictar  Dec 5, 2017

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