Q. ∠1 and ∠2 are vertical angles. If m∠1=(x+2)∘ and m∠2=(3x−8)∘, then find the measure of ∠1.Answer:
Set Angle Expressions Equal: Vertical angles are congruent, so their measures are equal. Set the expressions for the measures of angle 1 and angle 2 equal to each other to find the value of x.(x+2)2=(3x−8)2
Expand and Solve Equation: Expand both sides of the equation to solve for x.(x+2)(x+2)=(3x−8)(3x−8)x2+4x+4=9x2−48x+64
Rearrange and Set to Zero: Rearrange the equation to bring all terms to one side and set the equation to zero.x2−9x2+4x+48x+4−64=0−8x2+52x−60=0
Simplify and Divide: Divide the entire equation by −4 to simplify.−4(−8x2+52x−60)=−402x2−13x+15=0
Factor Quadratic Equation: Factor the quadratic equation to find the values of x.(2x−3)(x−5)=0
Solve for x: Set each factor equal to zero and solve for x.2x−3=0 or x−5=0x=23 or x=5
Check Validity of x: Since x represents a measure of an angle, it should be a positive value. Both 23 and 5 are positive, so we need to check which one is valid by substituting back into the original expressions for the angle measures.Substitute x=23 into (x+2)2:(23+2)2=(25)2=(2.5)2=6.25Substitute x=23 into (3x−8)2:(3(23)−8)2=(4.5−8)2=(−3.5)2=12.25Since these are not equal, x=23 is not the correct value.
Substitute x=5: Now, substitute x=5 into (x+2)2: (5+2)2=72=49 Substitute x=5 into (3x−8)2: (3(5)−8)2=(15−8)2=72=49 Since these are equal, x=5 is the correct value.
Find Measure of Angle 1: Now that we have the correct value of x, we can find the measure of angle 1.m/_1=(x+2)2m/_1=(5+2)2m/_1=72m/_1=49 degrees
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