CK12 - Geometry

Example 3

Whatis below?

Againyou may assumethat the interioranglesin a trianglemustsum to

Sinceyou knowthat the interioranglesin a trianglemustsum to you can find if you know
the measuresof the othertwo angles.Use the exteriorright angleto find the measureof its interiorangle.

Sincethe intersectinglinesformone right angle,all anglesformedwill measure and in particular,

. Now you knowtwo of the internalanglemeasuresin the triangle: and Use

subtractionto find.

measures

AdjacentComplementaryAngles

Rememberthat complementaryanglesare anglesthat sum to If complementaryanglesare adjacent,
they form perpendicularrays.You can then applyeverythingyou havelearnedaboutperpendicularlines to
the situationto find missinganglevalues.

Example 4

Whatis the measureof in the diagrambelow?

, so the two anglesin the upperrightare complementaryand sum to Since

is its verticalanglewill also measure Therefore.