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M2 chapter 5 - using geometry

Hi,
I'm doing some M2 revision and I'm quite stuck on exercise 5D, question 12. I have Solutionbank open as I write this and I think I understand their written method but I cannot see how they know that all of the following angles in the diagram are equal to phi. I believe they have used phi to represent theta (as theta was used to represent the desired angle in the question)

This is probably going to be very obvious when it's pointed out to me but I just cannot see it :redface:

Thanks very much for any help.

(edited 11 years ago)

Reply 1

ghostwalker

Original post by Where'sPerry?

Thanks very much for any help.

I can't see how the angle ABC relates to the other marked angles.

Is there more to the solution, or is that it?

Reply 2

Where'sPerry?

Original post by ghostwalker

I can't see how the angle ABC relates to the other marked angles.

Is there more to the solution, or is that it?

There is more, sorry, I just wanted to get the diagram in. Here's the rest. The red line is where it carries on from the previous screenshot

Reply 3

ghostwalker

Original post by Where'sPerry?

There is more, sorry, I just wanted to get the diagram in. Here's the rest. The red line is where it carries on from the previous screenshot

I think it's the case that angle ABC should be labelled theta, and all the others labelled phi remain as they are.

So, misprint on diagram.

Reply 4

Where'sPerry?

Original post by ghostwalker

I think it's the case that angle ABC should be labelled theta, and all the others labelled phi remain as they are.

So, misprint on diagram.

Thanks very much, I was getting so frustrated with this. The answers in the back of this book are horrendous, my teacher actually has a sheet of corrections for it. I shouldn't trust it so much :tongue: