By adding a third parallel line to the diagram, find ABC?

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1 Answer
Aug 1, 2017

angleABC=75^@

Explanation:

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Add the third line, parallel to lines M and N, through the vertex B, as shown in the figure. This splits angleABC into two smaller angles, x and y.

z=180-150=30^@

By the parallel lines properties, x=45^@ and y=z=30^@.

So angleABC=x+y=45+30=75^@