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Thursday 16 September 2021

Interior Angles of a Triangle

Earlier this week in Geometry, we did solving for the interior angles of a triangle. At first it was a bit confusing because I didn't quite understand the rules or how to go about working it out.

Thankfully, Mr Janse was kind and patient enough to help clarify my understanding. Here is an example of a few "easy" problems that we managed to solve. So the most important thing that you have to remember is that the interior angles which means the angles inside the triangle is equal to 360 degrees. 


Hopefully you will be able to follow my calculations/working out. I will only answer the first 2 sums and then you can have a go at the other 2.

a) x + 32 + 48 = 180                                                                                                                                                       x + 80 = 180                                                                                                                                                              x = 180 - 80                                                                                                                                                        x = 100  (this sum I found quite easy but the next when needed more complex thought)

b) For this sum I combined my knowledge of Algebra and formed an equation.

x + x + 28 + 90 (right angled triangle) = 180                                                                                                                                                   2x + 118 = 180                                                                                                                                                             2x = 180 - 118                                                                                                                                                   2x = 62                                                                                                                                                                 x = 62/2                                                                                                                                                             x = 31

As Mr J always says, we have to proof that our answers are correct, so here goes nothing folks. When you have solved for the unknown, in this case it is x, then we substitute it into the equation/rest of the part we are trying to solve. We already have 90 and the bottom right angle is 31. Next take x which is 31 add it to 28 (x + 28...........31 + 28 = 59).  Double check again - 90 + 31 + 59 = 180, so my answer is correct.

Let me know what you think of this activity. Also what are you guys doing for Mathematics during lockdown. I have added a video below. Hope this helps :)

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