Now, let’s understand angles and property of a quadrilateral by visualization… And since this visualization method is going to be very simple… So take a quadrilateral like this… Mark the angles as 1, 2, 3, 4… Now take three more copies… Rotate the first piece, so that angles 2 and 1 are now sitting together… Rotate the second piece further, so that 2, 1, 4 are now kept together… Rotate the third piece even further, so that 2, 1, 4, 3 are kept together to form a perfect circle, adding up to angle 360. So angles and property is thus proved, or you just visualized it… It’s so intuitive and so simple .
Now you can visualize angles and property of a quadrilateral in a much simpler fashion like this … Take a quadrilateral … Drop the diagonal so it‘ll get divided into two triangles… Now, in a triangle angles will add up to 180… So two triangles, angles will add up to 360… Now, to understand why in a triangle angles will add up to 180, you can visualize angles and property of a triangle like this…
To prove angles and property, that’s in simple language, angles in a triangle adding up to 180, I’m going to show you a method, the easiest ever, and I’m sure you have not seen it before… So, take a triangle … Name the angles as 1, 2, 3… Join the two mid-points here… Drop two perpendiculars … Fold this angle… Fold this angle… Fold this angle like this… Now, as you can see here… 1, 2, 3 are on along the the same straight line … So,
1 + 2 + 3 = 180 … Insanely simple, right? You try this using a paper… It’s so simple that it’s thrilling too… It’s almost like ‘wow’!