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Triangles: The Angles in a Triangle Sum Up to 180°

In right triangle DBC shown below, what is the value of $$x$$?
Incorrect. [[snippet]] Check your calculations.
Incorrect. [[snippet]] You might have gotten this answer if you calculated $$\angle ACB$$, rather than $$x$$.
Incorrect. [[snippet]] Carefully check your work.
Correct. [[snippet]] It's better to look at the big triangle and add up all angles to get 180. >$$\angle BAC + \angle ABC + \angle ACB = 180$$ >$$40+90+(20+x) = 180$$ >$$x+150 = 180$$ >$$x=30$$
Incorrect. [[snippet]] Carefully check your calculations.
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