MathDB

1951 AMC 12/AHSME

Part of AMC 12/AHSME

Subcontests

(50)

Proving a Locus

Which of the following methods of proving a geometric figure a locus is not correct? <spanclass=latexbold>(A)</span> Every point of the locus satisfies the conditions and every point not on the locus does not satisfy the conditions. <span class='latex-bold'>(A)</span>\ \text{Every point of the locus satisfies the conditions and every point not on the locus does not satisfy the conditions.} <spanclass=latexbold>(B)</span> Every point not satisfying the conditions is not on the locus and every point on the locus does satisfy the conditions. <span class='latex-bold'>(B)</span>\ \text{Every point not satisfying the conditions is not on the locus and every point on the locus does satisfy the conditions.} <spanclass=latexbold>(C)</span> Every point satisfying the conditions is on the locus and every point on the locus satisfies the conditions. <span class='latex-bold'>(C)</span>\ \text{Every point satisfying the conditions is on the locus and every point on the locus satisfies the conditions.} <spanclass=latexbold>(D)</span> Every point not on the locus does not satisfy the conditions and every point not satisfyingthe conditions is not on the locus. <span class='latex-bold'>(D)</span>\ \text{Every point not on the locus does not satisfy the conditions and every point not satisfying} \\ \text{the conditions is not on the locus.} <spanclass=latexbold>(E)</span> Every point satisfying the conditions is on the locus and every point not satisfying the conditions is not on the locus. <span class='latex-bold'>(E)</span>\ \text{Every point satisfying the conditions is on the locus and every point not satisfying the conditions is not on the locus.}

Six Triangular Sections

Through a point inside a triangle, three lines are drawn from the vertices to the opposite sides forming six triangular sections. Then: <spanclass=latexbold>(A)</span> the triangles are similar in opposite pairs <span class='latex-bold'>(A)</span>\ \text{the triangles are similar in opposite pairs} <spanclass=latexbold>(B)</span> the triangles are congruent in opposite pairs <span class='latex-bold'>(B)</span>\ \text{the triangles are congruent in opposite pairs} <spanclass=latexbold>(C)</span> the triangles are equal in area in opposite pairs <span class='latex-bold'>(C)</span>\ \text{the triangles are equal in area in opposite pairs} <spanclass=latexbold>(D)</span> three similar quadrilaterals are formed <span class='latex-bold'>(D)</span>\ \text{three similar quadrilaterals are formed} <spanclass=latexbold>(E)</span> none of the above relations are true <span class='latex-bold'>(E)</span>\ \text{none of the above relations are true}

Statements About Geometry Proofs

In connection with proof in geometry, indicate which one of the following statements is incorrect: <spanclass=latexbold>(A)</span> Some statements are accepted without being proved. <span class='latex-bold'>(A)</span>\ \text{Some statements are accepted without being proved.} <spanclass=latexbold>(B)</span> In some instances there is more than one correct order in proving certain propositions. <span class='latex-bold'>(B)</span>\ \text{In some instances there is more than one correct order in proving certain propositions.} <spanclass=latexbold>(C)</span> Every term used in a proof must have been defined previously. <span class='latex-bold'>(C)</span>\ \text{Every term used in a proof must have been defined previously.} <spanclass=latexbold>(D)</span> It is not possible to arrive by correct reasoning at a true conclusion if, in the given, there is an untrue proposition. <span class='latex-bold'>(D)</span>\ \text{It is not possible to arrive by correct reasoning at a true conclusion if, in the given, there is an untrue proposition.} <spanclass=latexbold>(E)</span> Indirect proof can be used whenever there are two or more contrary propositions. <span class='latex-bold'>(E)</span>\ \text{Indirect proof can be used whenever there are two or more contrary propositions.}

Statements About Doubling

Of the following statements, the one that is incorrect is: <spanclass=latexbold>(A)</span> Doubling the base of a given rectangle doubles the area. <span class='latex-bold'>(A)</span>\ \text{Doubling the base of a given rectangle doubles the area.} <spanclass=latexbold>(B)</span> Doubling the altitude of a triangle doubles the area. <span class='latex-bold'>(B)</span>\ \text{Doubling the altitude of a triangle doubles the area.} <spanclass=latexbold>(C)</span> Doubling the radius of a given circle doubles the area. <span class='latex-bold'>(C)</span>\ \text{Doubling the radius of a given circle doubles the area.} <spanclass=latexbold>(D)</span> Doubling the divisor of a fraction and dividing its numerator by 2 changes the quotient. <span class='latex-bold'>(D)</span>\ \text{Doubling the divisor of a fraction and dividing its numerator by 2 changes the quotient.} <spanclass=latexbold>(E)</span> Doubling a given quantity may make it less than it originally was. <span class='latex-bold'>(E)</span>\ \text{Doubling a given quantity may make it less than it originally was.}