How can I find the answer or what is the formula?

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The question is:
A land owner wants a good approximation of the width of his stream from point D to point C. At point B, he lays a carpenter’s square (used to make right angles) so that he can sight along BC and BA, and he determines that for right triangle ABD, AD = 9.3 feet and BD = 15.7 feet. What is the length of DC?

How can I find the answer or what is the formula to find the answer?

One Response to “How can I find the answer or what is the formula?”

  1. Daniel G Says:

    first use Pythagorean theorem for right triangle BAD. find AB=?. you can use that cos<DAB=AD/AB and cos<BAC=AB/AC. the both angles are the same. so AD/AB=AB/AC. from here you find AC. AC-AD=CD. e voila