Help! trig question.

[Inkaho]

Hi Everyone!

I'm trying to solve this triangle, I'm thinking that the cosine rule may apply? I just can't seem to work it out, Also the length of AB is 14.67106m. Please help!

 

[Deleted member 4993]

Hi Everyone!

I'm trying to solve this triangle, I'm thinking that the cosine rule may apply? I just can't seem to work it out, Also the length of AB is 14.67106m. Please help!
View attachment 5304

I have not done it yet - but looks like invoking Pythagorus would be sufficient to find the lengths - and then use law of cosines to calculate the angle.

 

[Steven G]

The diagram showing that DE=GH=3 is not required.

Denis, don't you need DE=GH=3 to know that FE=13 in order to find use the Pythagorean theorem to find BE??

 

[surem]

Hi!

Try this procedure; Draw a line from G to C, you will get Right- angle triangle GEC and find the length GC by Pythagorean theorem. Then find angles GCE and EGC . GAC is also a right angle triangle so used the same method. Let me know when you finished for us to continue.

 

[Deleted member 4993]

Denis, don't you need DE=GH=3 to know that FE=13 in order to find use the Pythagorean theorem to find BE??

No... we don't need DE = GH = 3. We can get FE = GE/2 = 26/2 = 13

 

[Steven G]

No... we don't need DE = GH = 3. We can get FE = GE/2 = 26/2 = 13

I am sure that you are correct but that does not mean I see it yet (I do not see things easily). I am picturing that rectangle moving to the right a bit while point A and C still touch the rectangle as in the diagram. Now it is clear that FE is not GE/2. What am I missing??

 

[surem]

Hi!

I don´t think line FE = GE/2 = 26/2 = 13 because line FB is not bisector of length GE.

 

[surem]

Hi!

After getting angles EGC and CGA. You have to find summation of the two angles to get angle EGA. Then you have triangle EGA , angle EGA, line GE and line GA. You can use such information to find line AE. Let us continue later.

 

[surem]

continue!!!

From the diagram above, angle EAB=angle EAC+angle CAB, but length AB=14.67106m and angle CAB = angle MAB so you have to apply Pythagorean theorem to get angle MAB= angle CAB. After getting angle EAB= angle EAC+ angle CAB, you have to consider triangle ABE. By applying cosine rule which will assist you to find length BE and angle AEB because you have already find length AE, angle EAB and length AB has been given in the question.
GOOD LUCK!