Melody

I can not take the credit Chris.

This is x^2 solution. A very nice solution it is too :)

Great work X-squared!  

Here is a video to explaing angle of depression and angle of elevation to you.

It is good. You should watch it.

Jenny, please do not delete questions. Someone might already be looking at it.

Just write an answer post thanking people for any time they may have spent but let them know you have now solved it yourself.  

You have not provided the actual question and  you do not even have enough knowledge to understand this fact.

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Your non-question.

The figure below is not drawn to scale. We are given that angle ADB is obtuse.
Which of the following statements must be true?

(i) BD (ii) CD 
Enter the letter of the multiple choice option below: 

A: (i) only 
B: (ii) only 
C: (i) and (ii) 
D: neither (i) nor (ii)

Write it properly and you might have a better chance of a timely answer.

Just edit it and take the $ signs away.

How many Sig Figs are in  \( 3.4\times {10}^{4}\)

Significant firgues with scientific notation is very easy.  There are 2 digits in 3.4 so there are 2 significant figures.

Only the significant part should be written in sci fi although if there is more to the question (like you have worked out the number yourself) you may need to be careful.

3.40000 * 10^4     has 6 significant figures   

Thanks EP I had forgotten that :)

Very nice Chris I like your method better. :)