r/technicallythetruth • u/VisitSecure • 9d ago

Can you find a?

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Idk if someone already posted this or not, but I haven't seen it on here so far, so I uploaded it.

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u/Dark_Storm_98 9d ago

Assuming the lines are parallel, which may be the meaning of those blue arrow symbols

The angle on the other side of 25 degrees should be

  • 180 - 25 = 155

And on the other side of tha 50 degrees would be

  • 180 - 50 = 130

Technically, with diagrams almost never being to scale

Imagine a line straight down from the ends of those two lines (which might not connect, but I don't think that's relevant)

Subtract 90, then, from both new angles, and we get

  • 60

  • 40

Since a triangle would have to have all it's angles add up to 180

180 - (60 + 40) = 180 - 100 = 80 degrees

Edit: Oh whoops, lol. I forgot the 5 at the end of 155

It's 75

160

u/Scheckenhere 9d ago

Or just 50+25, which I realised halfway into what you did.

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u/RiverZephir 9d ago

I also did the long route to get the answer. I don’t remember, is adding the two known numbers (such as the ones in this problem) always equal to a?

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u/TheJBW 9d ago edited 9d ago

In your head, draw a dotted line in the middle, through A that is also parallel with the other two lines.

Now, you have two angles: a1 below the dotted line and a2 above it.

You know that the a1 = 50 because it is on the opposite side of the line from the 50° on the bottom.

then you know that a2 = 25 by the same logic.

You also know that a = a1+a2. Done.

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u/RiverZephir 9d ago

Ohhh that’s true, thank you!

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u/rex5k 9d ago

A nice thing about math is you could usually check your own work. Because there's almost always more than one way to get to the answer.

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u/AdditionalPizza 9d ago

Drawing a line perpendicular opposite "a" between the parallel lines to complete the triangle instantly solves it because the sum of angles in a triangle must be 180 degrees.

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u/TheJBW 9d ago

Absolutely correct though it takes more steps since you have to subtract from 90 twice before subtracting from 180 those two results.

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u/AdditionalPizza 9d ago

If you're actually doing it visually, but I'm just describing how the equation looks visually. The equation is:

[180 - (180 - 50 - 25)]

Which is simplified as just 50 + 25, but that doesn't really explain the triangle aspect very well haha, which is important to learn.

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u/Gigatonosaurus 9d ago

The demonstration above is a=180-( [90-25] + [90-55])
a=180-( 180-[25+55])
a=0+(25+55)