And this was because the angles in a triangle all added to 180 degrees. An example of this is our final angle, where we said that angle 𝑋𝐶𝐵 was equal to 180 degrees minus 64 degrees minus 64 degrees which was equal to 52 degrees. In these kind of questions, you must give a reason for the angles that you found. The key thing to remember is that at each of our stages, we actually gave a reason. Just a quick recap of what we did, is we actually worked in stages to find different angles that we needed to allow us to work out the final angle of 𝑋𝐶𝐵. So therefore, we can say that the measure of angle 𝑋𝐶𝐵 is equal to 52 degrees. And this is because, again, angles in a triangle add up to 180 degrees. And this is gonna be equal to 180 minus 64 minus 64, which is therefore equal to 52 degrees. And this is the one that the question’s looking for. And therefore, the two angles 𝐵𝑋𝐶 and 𝐶𝐵𝑋 must be equal. And this is because triangle 𝐵𝐶𝑋 is isosceles. And this is actually also equal to 64 degrees. So next, we actually move on to angle 𝐶𝐵𝑋. The word isosceles is pronounced 'eye- sos -ell-ease' with the emphasis on the sos. Notice it always remains an isosceles triangle, the sides AB and AC always remain equal in length. Try this Drag the orange dots on each vertex to reshape the triangle. And we can actually see that the angles there, 116 and 64, are both on a straight line. A triangle which has two of its sides equal in length. Isosceles Triangle shape in TikZ Apex angle of Isosceles triangle Default. And we get this because the angles on a straight line add up to 180. 2 Arrow types 48 3 Arrows features 49 Angle increment When the angle of a bond. And this is gonna be equal to 180 minus 116, which is equal to 64 degrees. The next angle we’re taking a look at is angle 𝐵𝑋𝐶. So as you’ve seen, we’ve said one is because of a triangle being isosceles and the other one is angles in a triangle. And it’s actually worth noting at this point that when you’re calculating missing angles in a problem like this, you must give the reasoning for each angle. And this is because the angles in a triangle add up to 180 degrees. And this is gonna be equal to 180 minus 32 minus 32, which is equal to 116 degrees. Well, the next angle we’re gonna take a look at is angle 𝐴𝑋𝐶. Let’s get on and find some more to help us find the angle that we’re looking for, which is 𝑋𝐶𝐵.

And we know that because we actually have these markers on the diagram that show us that these two lengths are equal. And the reason it’s equal to 32 degrees because triangle 𝐴𝐶𝑋 is actually an isosceles triangle. It is given that the base angles of an isosceles triangle are equal and the vertex angle of an isosceles. And this is gonna be equal to 32 degrees. Let x be the base angle of an isosceles triangle. First of all, we could take a look at angle 𝐴𝐶𝑋.

Vertex angle of an isosceles triangle