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MATH / In triangle ABC, point D is on segment BC, the measure of angle BAC is 40 degrees, and triangle ABD is a reflection of triangle ACD over segment AD. What is the measure of angle B?…

Problem

Answer published by the source. Consult the official source to check your work against its answer.

problem

In triangle ABCABC, point DD is on segment BCBC, the measure of angle BACBAC is 40 degrees, and triangle ABDABD is a reflection of triangle ACDACD over segment ADAD. What is the measure of angle BB? [asy] size(101); pair B = (0,0); pair C = (2,0); pair D = (1,0); pair A = (1, tan(70*pi/180)); draw(A--B--C--cycle,linewidth(1)); label("AA",A,N); label("BB",B,W); label("CC",C,E); draw(A--D,linetype("2 4")+linewidth(1)); label("DD",D,S);[/asy]
Plain-text mathematical notation (without MathML)
In triangle ABC, point D is on segment BC, the measure of angle BAC is 40 degrees, and triangle ABD is a reflection of triangle ACD over segment AD. What is the measure of angle B?

[asy]
size(101);
pair B = (0,0); pair C = (2,0); pair D = (1,0); pair A = (1, tan(70*pi/180));
draw(A--B--C--cycle,linewidth(1));
label("A",A,N); label("B",B,W); label("C",C,E);

draw(A--D,linetype("2 4")+linewidth(1));
label("D",D,S);[/asy]
Original LaTeX notation
In triangle $ABC$, point $D$ is on segment $BC$, the measure of angle $BAC$ is 40 degrees, and triangle $ABD$ is a reflection of triangle $ACD$ over segment $AD$. What is the measure of angle $B$?

[asy]
size(101);
pair B = (0,0); pair C = (2,0); pair D = (1,0); pair A = (1, tan(70*pi/180));
draw(A--B--C--cycle,linewidth(1));
label("$A$",A,N); label("$B$",B,W); label("$C$",C,E);

draw(A--D,linetype("2 4")+linewidth(1));
label("$D$",D,S);[/asy]

level

Level 1

type

Geometry

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Source and history

task_id
76463e6c-e9a2-58b2-81b5-1497326cc135
task_key
geometry--test--76463e6c-e9a2-58b2-81b5-1497326cc135
task_revision_id
1
config / split
geometry / test

Official source

initial import