9514 1404 393
Answer:
(a) 90°, 90°
(b) 5, 1
(c) 10°, 20°
(d) 10°, 20°, 150°
Step-by-step explanation:
You need to consider ways in which each statement might not apply.
(a) An obtuse angle is greater than 90°. If both angles are 90°, then neither is obtuse.
counterexample: m∠1 = 90°, m∠2 = 90°
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(b) If the perimeter is 12, the sum of the side lengths must be 6. There are many ways to get two numbers that have a sum of 6. Here's one:
counterexample: length = 5, width = 1
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(c) All that is required is that the sum of angles be 30°. They don't have to be equal.
counterexample: m∠ABC = 10°, m∠CBD = 20°
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(d) We know the three angles of a triangle have a sum of 180°, but that does not require it to be an acute triangle. A triangle can also be right or obtuse.
counterexample: m∠P = 10°, m∠Q = 20°, m∠R = 150°
