135° for anyone wondering.
correct, just commenting the 100/80 intersection looks like 90/90, i think it was intentionally misleading, classic trying to get you problem
Yes I originally thought 90 but then noticed the absence of a right angle sign. Also 60+40=100 which means the last angle should be 80. Making that perpendicular 100/80
ah, the old "we drew a right angle but it represents some other angle" trick. I've been burned by that one more times than I can count.
I'd get out my red pen and write: "Bad diagram. -1pt See me after class."
Yes, simple doodle below for anyone wondering.
You start from left, and calculate them 1 by 1, based on the angles that you already know. It is quite simple actually, you just have to know they always add up to 180 (within triangle, and when you “split” the space over a straight line).
For context: it used to be 675° a few years back so the math checks out.
that's not how global warming works
Nope. The value is "undefined". You don't have enough info to arrive at 135 - you are assuming that the bottom angle (sum of the angles that touch) is 180 degrees. Since there isn't a datum saying the bottom "line" is straight, nor does it say the triangle on the right is an isosceles triangle, it is impossible to solve.
I think assuming 2 line segments which make up a larger straight line segment to be parallel is generally accepted practice, and that would trump the angles that are drawn inaccurately.
Of course, it'd be better to put a hash through them both to indicate they're parallel, especially given the deceptively drawn most-likely-not-a-right-angle.
You do have that datum. you are right assuming that that angle isn't 90°. It's actually 100° on the right side, so X = 135
I hated pictures like this in school. The numbers are just slapped on an inaccurate image and somehow they expect people to ignore the obvious right triangles and just focus on the math part of it.
Fun fact: In Turkey's university admittance exam, all angles have to be absolutely accurate, and measurements have to be scaled down perfectly to the visible shape in a geometry question.
all angles have to be absolutely accurate
To what tolerance, though? Writing math exams has now become an engineering problem.
If it was to scale you could just use a protractor and skip the whole math part, which is the entire part of the lesson…
Then they could use decimals so it's unlikely to get it right without calculating, 60.17°, 40.29°, 35.43°
If the student eventually does geometry for money, they'll discover that customer CAD files invariably have some bizarre error like this.
I was scared I forgot basic trig stuff.
It's even easier than going the triangle route.
A four-corner shape always has 360° internally.
So the internal angle of corner X is 360-(60+40+35).
The exterior angle therefore is 360-360-(60+40+35) = 60+40+35 = 135
That's based on the assumption that the two angles in the middle add up to 180, which can't be assumed by inspection alone as demonstrated by the visibly square 80° angle
Nice one, forgot this was an option too. You are missing a set of brackets though ;)
I love that every comment focus on the math puzzle. Since the other stuff is clearly uninteresting.
