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Theorems and definitions

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Question
Answer
Similar Triangles Theorem   if the altitude is drawn to the hypotenuse of a right triangle, then the two triangles formed are similar to the original triangle and to each other △CBD ~ ABC △ACD~ABC △CBD~ACD  
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Corollarry 1   when the altitude is drawn to the hypotenuse of a right triangle, then the length of the altitude is the geometric mean between the segments of the hypotenuse  
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Corollary 2   when the altitude is drawn to the hypotenuse of a right triangle, each leg is the geometric mean between the hypotenuse and the segment of the hypotenuse that is adjacent to that leg  
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Pythagorean Theorem   In a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the legs C²=a²+b²  
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Pythagorean Triple   Is a set of three positive integers a, b, and c that satisfy the equation C²=a²+b²  
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Converse of the Pythagorean Theorem   If the square of the length of the longest side of a triangle is equal to the sum of the squares of the lengths of the other two sides, then the triangle is a RIGHT triangle if C^2=a^2+b^2 then (triangle)ABC is a right triangle  
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Acute Triangles Theorem   If the square of the length of the longest side of a triangle is less than the sum of the squares of the lengths of the other two sides, then the triangle is acute. C^2<a^2+b^2  
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Obtuse Triangle Theorem   If the square of the length of the longest side of a triangle is greater than the sum of the squares of the lengths of the other two sides, then the triangle is obtuse C²>a²+b²  
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45⁰- 45⁰ - 90⁰   In a 45 45 90 triangle, the hypotenuse is root 2 times as long as each leg  
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60⁰-90⁰   the hypotenuse is 2 times as long as the shorter leg and the longer leg is root 3 times as long as shorter leg  
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Trigonometric Ratios   sin= side opposite <A / hypotenuse = a/c cos= side adjacent <A / hypotenuse = b/c tan= side opposite <A / side adjacent <A = a/b  
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Angle Elevation   is the angle that your line of sight makes with a horizontal line when you stand and look up at a point in the distance  
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Triangle Sum Theorem   the sum of the measure of the interior angles of a triangle is 180⁰  
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Exterior Angles Theorem   The measure of an exterior angle of a triangle is equal to the sum of the measures of two non-adjacent interior angels  
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Third Angles Theorem   If two angles of one triangle are congruent to two angles of another triangle, then the third angles are also congruent  
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Side Side Side Congruence Postulate (SSS)   If three sides of one triangle are congruent to three sides of second triangle, then the two triangles are congruent  
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Side Angle Side (SAS) Congruence Postulate   If two dies and the included angle of one triangle are congruent to two sides and the included angle of a second triangle, then the two triangles are congruent  
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Angle Side Angle (ASA) Congruence Postulate   If two angles and he included side of one triangle is congruent to two angles and the included side of a second triangle, then the two triangles are congruent  
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Angle Angle Side (AAS) Congruence Theorem   If two angles and a non-included side of one triangle are congruent to two angles and the corresponding non-included side of a second triangle, then the two triangles are congruent  
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Corresponding Parts of Congruent Triangles are Congruent (CPCTC)   If two triangles are congruent, then all corresponding parts f those triangles are also congruent  
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Base Angle   two angles that are adjacent to the base of the triangle  
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Base Angles Theorem   If two sides of a triangles are congruent, then the angles opposite them are congruent  
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Corollary to the Base Angles Theorem   If a triangle is equilateral, then it is equiangular  
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Corollary to Theorem   If a triangle is equiangular, then it is equilateral  
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Hypotenuse-Leg (HL) Congruence Theorem   If the hypotenuse and a leg of a right (RT) triangle are congruent to the hypotenuse and leg of a second right triangle, then the two triangles are congruent  
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