Expert: Josh - 1/10/2006

Question
plz help me i am the dumbest at maths plz help me
there is a angle which make a cross the left side of the angle is 110 digrees the top left is called a top left called c bottom left e bottom right is d. i have to find A B and C plz help me answer quick as u can i need to give it in on tomarrow even if u are late still answer me and tell me how u did it because i have lots others.THANKS YOU!

Answer
I cannot comprehend this diagram based on the information you have given. But I guess it looks something like this.

C         A
.
.
....B
.
.
...........D
E

If I guessed correctly, you have a quadrilateral (four-sided figure) with vertices (corners) given by A,C,E and D. Point B is the intersection between the line CD and line AE. I think you are telling me that the obtuse angle subtended by CBE (one measuring between 90 and 180 degrees) is given by 110 degrees.

Based on this assumption, we know that angle CBA must be 180-110=70 degrees, because the straight line EBA (not drawn to scale) must contain 180 degrees.

The other angles cannot be exactly determined, unless you are given other information which you have left out. There might be implicit assumptions from the diagram which I can't see. For instance, the angles BCE and CEB might be the same. To help you understand this stuff, let's pretend that this is the case.

IF this is the case, then, angle BCE = (180-110)/2. Here we quote the result that the internal angles in a triangle always add up to 180 deg. This sum consists of angle BCE, angle CEB and angle EBC.

Let us write this as
180=^BCE+^CEB+^EBC, where ^ denotes "angle".
Since, we were told that ^CBE=110, if ^BCE=^CEB,
we must have 180 = ^CEB+^CEB+110. Rearranging this, we obtain (180-110)=2*^CEB. So, ^CEB=35 degrees.

As I said, there might be things that you can deduce from the diagram. I can't see one, so i'll just make up interesting cases to get certain points across.

Further to the assumptions above, IF angle ECA is a right angle (90 deg), then, we must have
^ACE=^ACB+^BCE=90   Note: we just worked out that ^BCE=35,
so, 90=^ACB+35, ^ACB=55 degrees.

N.B. Do not simply replicate what I've done. The assumptions I made are blind assumptions, since I can't actually see the diagram in your book. You have to apply the right rule in the right situation. I've only given you some basics to get you started.

One more thing. Don't ever called yourself dumb. Just do the best you can, achieve your own goals... let's not worry what others think. Chin up:)