Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
Chapter Review
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Exercise 17 Page 434

The sum of the unknown angles is equal to m∠ ABC.

m∠ ABD=88^(∘)
m∠ CBD=23^(∘)

Practice makes perfect

We have been asked to find m∠ ABD and m∠ CBD. The expression m∠ ABD is the measure of the angle between rays BA and BD. Similarly, m∠ CBD is the measure of the angle between rays BD and BC.

The sum of m∠ ABD and m∠ CBD is equal to m∠ ABC. m∠ ABD+ m∠ CBD= m∠ ABC It is given that m∠ ABC equals 111^(∘). Let's substitute this and the given expressions for the two smaller angles into the equation. Then we can solve for x.
m∠ ABD+ m∠ CBD= m∠ ABC
(-10x+58)^(∘)+ (6x+41)^(∘)= 111^(∘)
Solve for x
-10x+58+6x+41=111
-4x+99=111
-4x=12
x=-3
Having solved the equation, we can calculate the individual angles by substituting x= -3 into the expressions for the unknown angles. m∠ ABD &: -10( -3)+58=88^(∘) m∠ CBD &: 6( -3)+41=23^(∘)