Not sure how to answer question 4
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Answer:
Option D is correct
Step-by-step explanation:
Applying the cosine theorem for triangle ABC, you would have:
cos (angle BAC) = (BA^2 + CA^2 - BC^2)/(2*BA*CA)
= (10^2 + 18^2 - 20^2)/(2*10*18)
= 24/360
=> angle BAC = ~86 deg
Hope this helps!