Use a protractor to measure ∠ABC as shown in the picture below. Print out this page if you need to.
First, we can split the angle into two parts by drawing a dotted line along the line BC. Here, we know that we can get ∠ABC by adding these two angles together.
Let's measure the first part. We place the protractor on the vertex B and make sure that its base line is along BC as shown:
By reading the inner scale, we can see that this angle is 180°.
Next, we measure the second angle. We rotate the protractor and make sure that the base line is along AB as shown:
By reading the outer scale, we can see that this angle is 45°.
Hence, we can get ∠ABC by adding 180° with 45°.
Clearly, the answer is D.
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