McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
3. Special Right Triangles
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Exercise 63 Page 648

∠4,∠ 11

Practice makes perfect

Let's begin with recalling the Exterior Angle Inequality Theorem. This theorem tells us that the measure of an exterior angle of a triangle is greater than the measure of either of its corresponding remote interior angles.

Now, let's look at the given picture. As we can see, ∠4 is an exterior angle of a triangle containing ∠6. Therefore, the measure of ∠4 is greater than the measure of ∠6.

Notice that, since ∠11 is an exterior angle of a triangle containing ∠4, m∠11 is greater than m∠4. This indicates that m∠11 is also greater than m∠6. m ∠11>m ∠4>m ∠6 Therefore, there are two angles, 4 and 11, that have a greater measure than ∠6. Notice that ∠1 is not an exterior angle of a triangle containing ∠6, so we cannot use the recalled theorem.