Q. In △DEF,m∠D=(x−9)∘,m∠E=(3x−6)∘, and m∠F=(10x−15)∘. Find m∠E.Answer:
Identify Triangle Angles: Identify the relationship between the angles in a triangle. The sum of the angles in any triangle is always 180 degrees.
Set Up Equation: Set up the equation based on the given angle expressions.∠Dm+∠Em+∠Fm=180∘Substitute the given expressions for ∠Dm, ∠Em, and ∠Fm.(x−9)∘+(3x−6)∘+(10x−15)∘=180∘
Combine Like Terms: Combine like terms to simplify the equation.x−9+3x−6+10x−15=180Combine the x terms and the constant terms.14x−30=180
Solve for x: Solve for x.Add 30 to both sides of the equation.14x−30+30=180+3014x=210Divide both sides by 14.x=14210x=15
Substitute x Value: Substitute the value of x back into the expression for m/∠E to find its measure.m/∠E=(3x−6)∘m/∠E=(3(15)−6)∘m/∠E=(45−6)∘m/∠E=39∘
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