Angles in a Snakey Segment

Geometry Level 1

If A B \overline{AB} is parallel to D E \overline{DE} , then what is the measure of angle B C D BCD in degrees?


The answer is 120.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

14 solutions

This is the easiest way:

Nice solution!

Saubia Ansari - 5 years, 9 months ago

I also used a perpendicular line to solve this problem, only this looks much simpler than what I did as I drew my perpendicular line from point B creating two triangles that one could easily determine each of the angles created with a few minor calculations. However, I do like this answer as it is simple and very straight forward with little explanation needed

Gary Steede - 5 years, 9 months ago

Log in to reply

Sometimes math is easier to understand that way :) Thanks!

Kerry Lasiter Billingsley - 5 years, 9 months ago

it is the best &easiest solution.thanks a lot.

NIRAKAR SWAIN - 5 years, 8 months ago

I used a perpendicular through C, but your solution is much more elegant.

Bram Brusselmans - 4 years, 10 months ago

I will add a line segment parallel with the line A B , D E AB, DE called X C ) XC )

Then, X C D = 50 ° \displaystyle \angle XCD=50° because X C D \displaystyle \angle XCD and C D E \angle CDE are alternate interior angles

Then B C X = 70 ° \displaystyle \angle BCX=70° because X C B + A B C = 180 ° \displaystyle \angle XCB+ \angle ABC=180° ( Consecutive interior angles )

Lastly, take 50 ° + 70 ° = 120 ° \displaystyle 50°+70°=\boxed{120°}

This is how I solved it.

Maureen Kimball - 4 years, 9 months ago
Josue Ramirez
Sep 9, 2015

C D E a n d B P C \angle CDE\quad and\quad \angle BPC\quad are alternate interior angles, so B P C \angle BPC = 50

Then P B C \angle PBC = 180 - 110 = 70

Then B C P \angle BCP = 180 - 70 - 50 = 60
Finally x = 180 - 60 = 120 \boxed{120}

I take issue with this because visually, it's an acute angle.

Bo Grzybowski - 4 years, 10 months ago

Did the same thing

Sonal Singh - 5 years, 9 months ago

Angle APD is also 50 degrees. Angle PBC is 180 - 110 = 70. Therefore angle BCP is 180 - 120 = 60. Therefore BCD is 180 - 60 = Are you kidding me? 120!! Something's fishy because I agree it should be less than a right angle.

Gary Krejsa - 4 years, 9 months ago

Did in the same way!

Saubia Ansari - 5 years, 9 months ago

I also did it the same way. However, in the diagram, it appears to be an acute angle, not an obtuse angle👍

Ishan Maheshwari - 4 years, 2 months ago
Gary Steede
Sep 12, 2015

The is why I love math so much there are many different ways to solve problems like this. I personally drew a line perpendicular to line segment AB to create two triangles. The bottom triangle containing angle CDE and the newly created 90 degree angle allowed me to find the third angle of that triangle by subtracting those two angles from 180, since the sum of all interior angles of a triangle is 180 degrees. So 180-90-50=40, with this information I also know that the opposite angle from where this perpendicular line crosses line segment CD is also 40 degrees giving us one of the angle of the top triangle created. Now let's look at the other angle at point B, since I drew a perpendicular line from point B we can subtract 90 from 110 to discover the top angle of the top triangle, giving us 110-90=20. With this information we can now subtract the measurement of both of the new angles of the top triangle from 180 to give us the solution for what angle x is. This would be 180-40-20=120, so x=120.

Omar Monteagudo
Jan 18, 2017

Atikan Benz
Sep 9, 2015

Joe Potillor
Nov 30, 2016

Surya Ghosh
Aug 6, 2016

The ans is 120, how ever the picture is a bit misleading. The angle does not look like 120, it looks like even less than 90 !

Razzi Masroor
Jun 22, 2016

Problems are better if they have parallel solutions, :]

Luvneesh Kumar
Sep 17, 2015

NCERT question Grade IX

Corn Jones
Sep 9, 2015

Am I the only one who did it this way? Draw a segment from A to D. This makes ABCD into a quadrilateral, therefore the total angles of ABCD = 360 degrees. We know <ADE+<BAD=180-50=130, while <ABC=110. Therefore, <BCD=360-130-110=120

I guess you are the only one who did it this way

Sonal Singh - 5 years, 9 months ago
Achille 'Gilles'
Sep 9, 2015

Trace a line parallel to AB that cross the point C. Let’s call it XC where X is the leftmost point.

∠XCB + ∠ABC = 180° or 180° - ∠ABC =∠XCB

∠XCB = 180° - 110° = 70°


∠XCD = ∠CDE = 50°


∠BCD = ∠XCD + ∠XCB = 50° + 70° = 120°

Celso Camargo
Sep 7, 2015

Be F the point that DC intercepts AB, Angle BFC is 50º. Angle CBF is 180º - 110º = 70º. So angle BCF is 180º - 50º - 70º = 60º. Thus x = 180º - BCF = 180º - 60} = 120º

Ritam Baidya
Sep 5, 2015

draw a st. line passing through c parallel to eother ab or de then get the sum of 50 and 70 to get your ans..simple

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...