body{margin:0;} noscript{z-index: 10000; position: fixed; display: block; height: 100%; width: 100%; background: #fff;} noscript .fa{font-size: 40px; display:block; color: #daa520;} noscript div{margin-top: 6%; padding-left: 20px; padding-right: 20px; text-align: center;} ! You must have JavaScript enabled to use this site.

Big Ideas Math Integrated I, 2016

BI

Big Ideas Math Integrated I, 2016 View details

5. Proving Geometric Relationships

Continue to next subchapter

Exercise 16 Page 483

What kind of angles are $(13 x + 45)^{\circ}$ and $(12 x - 40)^{\circ}$ ?

$x = 7,$ see solution.

Practice makes perfect

According to the calculations, it would seem that

(13 x + 45)^{\circ}

and

(12 x - 40)^{\circ}

are complementary angles since they add up to

9 0^{\circ} .

However, looking at the figure, we can see that these angles are a linear pair and are actually supplementary angles. To solve for

x,

we set their sum equal to

18 0^{\circ} .

(13 x + 45) + (12 x - 40) = 180

Remove parentheses

13 x + 45 + 12 x - 40 = 180

Simplify terms

25 x + 5 = 180

$LHS - 5 = RHS - 5$

25 x = 175

$LHS / 25 = RHS / 25$

x = 7

Subchapter links

Communicate Your Answer p.477

Monitoring Progress p.478-482

Exercises p.483-486