Difference between revisions of "2014 AMC 8 Problems/Problem 9"

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In <math>\bigtriangleup ABC</math>, <math>D</math> is a point on side <math>\overline{AC}</math> such that <math>BD=DC</math> and <math>\angle BCD</math> measures <math>70^\circ</math>. What is the degree measure of <math>\angle ADB</math>?
 
In <math>\bigtriangleup ABC</math>, <math>D</math> is a point on side <math>\overline{AC}</math> such that <math>BD=DC</math> and <math>\angle BCD</math> measures <math>70^\circ</math>. What is the degree measure of <math>\angle ADB</math>?
  
<asy>size(300);defaultpen(linewidth(0.8));pair A=(-1,0),C=(1,0),B=dir(40),D=origin;draw(A--B--C--A);draw(D--B);dot("$A$"...</asy>
+
<asy>
 +
size(300);
 +
defaultpen(linewidth(0.8));
 +
pair A=(-1,0),C=(1,0),B=dir(40),D=origin;
 +
draw(A--B--C--A);
 +
draw(D--B);
 +
dot("$A$", A, SW);
 +
dot("$B$", B, NE);
 +
dot("$C$", C, SE);
 +
dot("$D$", D, S);
 +
label("$70^\circ$",C,2*dir(180-35));\</asy>
  
 
<math>\textbf{(A) }100\qquad\textbf{(B) }120\qquad\textbf{(C) }135\qquad\textbf{(D) }140\qquad \textbf{(E) }150</math>
 
<math>\textbf{(A) }100\qquad\textbf{(B) }120\qquad\textbf{(C) }135\qquad\textbf{(D) }140\qquad \textbf{(E) }150</math>

Revision as of 19:22, 26 November 2014

In $\bigtriangleup ABC$, $D$ is a point on side $\overline{AC}$ such that $BD=DC$ and $\angle BCD$ measures $70^\circ$. What is the degree measure of $\angle ADB$?

size(300);
defaultpen(linewidth(0.8));
pair A=(-1,0),C=(1,0),B=dir(40),D=origin;
draw(A--B--C--A);
draw(D--B);
dot("$A$", A, SW);
dot("$B$", B, NE);
dot("$C$", C, SE);
dot("$D$", D, S);
label("$70^\circ$",C,2*dir(180-35));\ (Error making remote request. Unknown error_msg)

$\textbf{(A) }100\qquad\textbf{(B) }120\qquad\textbf{(C) }135\qquad\textbf{(D) }140\qquad \textbf{(E) }150$