Q. B 242. QUAD is inscribed in circle P. If ∠A=x2−15 and ∠Q=100−21x, find ∠Q.
Identify Relationship: Identify the relationship between angles in a circle.In a circle, opposite angles of an inscribed quadrilateral sum up to 180∘.
Set up Equation: Set up the equation using the relationship. ∠A+∠Q=180(x2−15)+(100−(21)x)=180
Simplify Equation: Simplify the equation.x2−21x+100−15=180x2−21x+85=180
Solve for x: Solve for x.x2−21x−95=0Using the quadratic formula, x=2a−b±b2−4acHere, a=1, b=−21, c=−95x=2⋅10.5±(0.5)2+4⋅1⋅95x=20.5±0.25+380x=20.5±380.25x=20.5±19.5x=10 or x=2a−b±b2−4ac0
Substitute x: Substitute x back into the expression for /Q. /Q=100−(1/2)x For x=10, /Q=100−(1/2)⋅10=100−5=95 For x=−19, /Q=100−(1/2)⋅(−19)=100+9.5=109.5
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