Conditional If an angle is a right angle then its measure is 90 The conditional

# Conditional if an angle is a right angle then its

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Conditional: If an angle is a right angle, then its measure is 90°. The conditional is true. Converse: If the measure of an angle is 90°, then it is a right angle. The converse is true. Since the conditional and its converse are true, the biconditional is true.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions Check It Out! Example 3b y = –5 y 2 = 25 Determine if the biconditional is true. If false, give a counterexample. Conditional: If y = –5, then y 2 = 25. The conditional is true. Converse: If y 2 = 25, then y = –5. The converse is false. The converse is false when y = 5. Thus, the biconditional is false.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions In geometry, biconditional statements are used to write definitions . A definition is a statement that describes a mathematical object and can be written as a true biconditional.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions In the glossary, a polygon is defined as a closed plane figure formed by three or more line segments.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions A triangle is defined as a three-sided polygon, and a quadrilateral is a four-sided polygon.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions Think of definitions as being reversible. Postulates, however are not necessarily true when reversed. Helpful Hint
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions Write each definition as a biconditional. Example 4: Writing Definitions as Biconditional Statements A. A pentagon is a five-sided polygon. B. A right angle measures 90°. A figure is a pentagon if and only if it is a 5-sided polygon. An angle is a right angle if and only if it measures 90°.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions Check It Out! Example 4 4a. A quadrilateral is a four-sided polygon. 4b. The measure of a straight angle is 180°. Write each definition as a biconditional. A figure is a quadrilateral if and only if it is a 4- sided polygon. An  is a straight if and only if its measure is 180°.
Holt McDougal Geometry 2-4 Biconditional Statements and Definitions Lesson Quiz 1. For the conditional “If an angle is right, then its measure is 90°,” write the converse and a biconditional statement. 2. Determine if the biconditional “Two angles are complementary if and only if they are both acute” is true. If false, give a counterexample. False; possible answer: 30° and 40° Converse: If an measures 90°, then the is right. Biconditional: An is right iff its measure is 90°. 3. Write the definition “An acute triangle is a triangle with three acute angles” as a biconditional. A triangle is acute iff it has 3 acute s.

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