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Trigonometry Trigonometry: Right-angled triangle

Brian Bart

New member
Aug 18, 2019
Hi Guys
I need help with this question
so if you can help me with the answer please please.

photo_2019-08-18_13-01-53 (2).jpg



Well-known member
MHB Math Helper
Mar 1, 2012
North Texas
part (i) of the student's response is correct.

part (ii) has an algebra error in determining the length of DC

if $DC^2 = DB^2 - CB^2$, then $DC \ne DB - CB$

the trig for part (iii) is correct ... can't say I agree with using 120 degrees for angle ADB since it induces rounding error in determining the length of AB.

Using the equation $\sin(40) = \dfrac{BC}{AB} \implies AB = \dfrac{BC}{\sin(40)}$ will not induce that error.
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