<h2>E
xplanation:</h2><h3>1.</h3>
The little square box in the corner between the vertical line and the horizontal one is a symbol indicating that angle is a right angle. It has a measure of 90°. The angles designated 1 and 2 together add up to that 90°. When angles sum to the value 90°, they are called "complementary" angles.
Since angles 1 and 2 also share a side and a vertex, they are also "adjacent" angles.
The appropriate choices are ...
- complementary angles
- adjacent angles
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<h3>2.</h3>
The same lines define the sides of angles 1 and 2, and they share a vertex. However, they are not adjacent. They are ...
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<h3>3.</h3>
The angles marked 157° and x° together add up to make a line, so they are supplementary (their total is 180°). They also share a vertex and a side, so they are adjacent. The appropriate choices are ...
- supplementary angles
- adjacent angles
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<h3>4.</h3>
When two angles total 180°, they are <em>supplementary</em>, whether they have any common parts or not. Since 98° + 82° = 180°, ...
- The angles are supplementary
