To Prove: m ∠1 = 90° - m ∠2 1. Ray ST is perpendicular to Ray SR. Definition of perpendicular lines 2. ∠RST is a right angle. Given 3. m∠RST = 90° Definition of right angle 4. m∠1 + m∠2 = m∠RST Substitution 5. m∠1 + m∠2 = 90° Angle addition theorem 6. m∠1 = 90° - m∠2 Subtraction property of equality

The graph below shows the line of best fit for data collected on the number of cell phones and cell phone cases sold at a local electronics store on twelve different days. number of cell phone cases sold 50 * 0 5 10 15 20 25 30 35 40 45 number of cell phones sold which of the following is the equation for the line of best fit? a. y = 0.8x b. y = 0.2x c. y=0.5x d. y = 0.25x