Geometry: An Interactive Journey to Mastery

Glossary

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x all side lengths encountered in turn match in the same ratio k.

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The common ratio k of the side lengths is called the scale factor.

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UDGLXV,IWKHDQJOHRIHOHYDWLRQRIWKHSRLQWDERYHWKHSRVLWLYHKRUL]RQWDOD[LVLVx, then the height of the point

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VLQHRIDQDQJOHͼ௘LQWULJRQRPHWU\௘ͽͼ௘௘ͽ: If x is a non–right angle in a right triangle, then the ratio of the length

of the side of the triangle opposite angle x to the length of the hypotenuse of the right triangle is called the sine

of the angle and is denoted sin x .ͼ௘7KLVYDOXHPDWFKHVWKHKHLJKWRIDSRLQWRQDXQLWFLUFOHZLWKDQJOHRI

elevation x௘ͽ6HHDOVRVLQHRIDQDQJOHͼ௘LQFLUFOHRPHWU\௘ͽ.

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RIDQ\RQHRILWVWULDQJXODUIDFHVͼ௘ZLWKDEDVHHGJHFRQVLGHUHGWKHEDVHRIWKHWULDQJOH௘ͽ6HHDOVRcone, pyramid.

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sphere.

VTXDQJXODUQXPEHUͼ௘௘ͽ$QXPEHUWKDWLVERWKVTXDUHDQGWULDQJXODU6HHDOVRsquare number,

triangular number.

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a square array.

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RQWRWKH¿JXUHLWVHOI6HHDOVRmapping.

WDQJHQWRIDQDQJOHͼ௘LQWULJRQRPHWU\௘ͽͼ௘௘ͽ: If x is a non–right angle in a right triangle, then the ratio of the

length of the side of the triangle opposite angle xWRWKHOHQJWKRIWKHVLGHDGMDFHQWWRWKHDQJOHͼ௘GLIIHUHQWIURP

WKHK\SRWHQXVHRIWKHULJKWWULDQJOH௘ͽLVFDOOHGWKHWDQJHQWRIWKHDQJOHDQGLVGHQRWHGtan x.