Difference between revisions of "1957 AHSME Problems/Problem 21"

(Problem 21)
(Solution)
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(4) is a restatement of the original conditional
 
(4) is a restatement of the original conditional
 
Therefore, (3) and (4) are correct. <math>\boxed{\textbf{(E) } (3), (4)}</math>
 
Therefore, (3) and (4) are correct. <math>\boxed{\textbf{(E) } (3), (4)}</math>
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==See Also==
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{{AHSME box|year=1957|num-b=20|num-a=22}}
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{{MAA Notice}}
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[[Category:AHSME]][[Category:AHSME Problems]]

Revision as of 14:36, 10 June 2024

Problem 21

Start with the theorem "If two angles of a triangle are equal, the triangle is isosceles," and the following four statements:

1. If two angles of a triangle are not equal, the triangle is not isosceles.

2. The base angles of an isosceles triangle are equal.

3. If a triangle is not isosceles, then two of its angles are not equal.

4. A necessary condition that two angles of a triangle be equal is that the triangle be isosceles.

Which combination of statements contains only those which are logically equivalent to the given theorem?

$\textbf{(A)}\ 1,\,2,\,3,\,4 \qquad \textbf{(B)}\ 1,\,2,\,3\qquad \textbf{(C)}\ 2,\,3,\,4\qquad \textbf{(D)}\ 1,\,2\qquad\textbf{(E)}\ 3,\,4$

Solution

(1) is the inverse (2) is the converse (3) is the contrapositive (4) is a restatement of the original conditional Therefore, (3) and (4) are correct. $\boxed{\textbf{(E) } (3), (4)}$

See Also

1957 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 20
Followed by
Problem 22
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
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