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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
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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