Q. In △CDE,CE is extended through point E to point F,m∠CDE=(2x+12)∘, m∠DEF=(7x−6)∘, and m∠ECD=(2x+3)∘. Find m∠CDE.Answer:
Identify Relationship: Identify the relationship between the angles.Since CE is a straight line, the angles CDE and DEF form a linear pair and therefore add up to 180 degrees.
Set Up Equation: Set up the equation based on the linear pair relationship.m/_CDE+m/_DEF=180∘Substitute the given expressions for m/_CDE and m/_DEF.(2x+12)∘+(7x−6)∘=180∘
Combine and Solve: Combine like terms and solve for x.2x+12+7x−6=1809x+6=180
Subtract and Simplify: Subtract 6 from both sides of the equation.9x+6−6=180−69x=174
Divide for x Value: Divide both sides by 9 to find the value of x.99x=9174x=19.333…
Substitute for CDE: Substitute the value of x back into the expression for m/_CDE. m/_CDE=(2x+12)@ m/_CDE=(2(19.333...)+12)@ m/_CDE=(38.666...+12)@ m/_CDE=50.666...@
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