Finding the Missing Angles in a Triangle.

We know that in a triangle, the three angles always add up to 180°.  We can use this knowledge to find missing angles.

unknown triangleWe can see here that we know two of the three angles.  Since we know that the sum of the three angels needs to be 180°, we can work our way towards the missing angle.  Lets try it by adding.

Attempt #1

55°+60°+__= 180°        So lets ask ourselves, what is 55+60?  Well I know that 50 + 50 gives us 100. Now I know we did not have 50+50 but  add the 5 from the 55  I know I will have 105.  If I add the 10 that would turn the other 50 into 60 to what I have, I would get 115.

If you are capable of adding 55+60, you can do that as well.  Either way we get 115.  Now we can ask ourselves:

115 + ? = 180  Once you do figure that out, you will have found the missing angle.  115 +65 = 180.  65° is our missing angle.

We can also solve it by subtracting.

Attempt #2

We know that we will have 180° in the triangle.  If one angle uses up 55° of those 180, we are left with 125°

(180 – 55 = 125).

We know that the other angle uses up 60° of that triangle.  We had 125° left, and now we can take away the 60°

(125° – 60° = 65°).

We have discovered that 65° is our missing angle.

You can further review at this Math site!


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