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Angles: Setting up Equations. Right Angles. Complementary angles: Set equation equal to 90. 3x+7. 4x+13. Add the two expressions. (3x + 7) + (4x +13) = 90. 7x + 20 = 90 -20 -20 7x = 70 x = 10. Combine like terms: 7x + 20 = 90. Solve for x:.
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Right Angles Complementary angles: Set equation equal to 90. 3x+7 4x+13 Add the two expressions. (3x + 7) + (4x +13) = 90 7x + 20 = 90 -20 -20 7x = 70 x = 10 Combine like terms: 7x + 20 = 90 Solve for x:
Perpendicular Lines A Same as Complementary: adds to 90 degrees. AB __BC ABD = 7x+2 DBC = 5x+4 Set up the equation: 7x+2 + 5x+4 = 90 Combine Like Terms: 12x +6 = 90 Solve. D 7x+2 5x+4 B C
Supplementary Angles Supplementary Angles are along a straight line. Add to 180 degrees. 5x+7 3x+13 • Set up: 5x+7 + 3x+13= 180 • Combine: 8x +20 =180 • Solve: -20 -20 • Divide: 8x = 160 • x = 20
Vertical Angles With vertical angles, the ones across from each other are equal. E D 9x-4 7x+10 B 9x - 4 = 7x +10 A C Variables on different sides of the equation. 9x – 4 = 7x + 10 -7x -7x 2x – 4 = 10 +4 +4 2x = 14 x= 7