Sin20° + sin 140° + cos170°=0​

Can someone me and plz do the problem

Asurvey of 45 teens found that they spent an average of 25.6 hours per week in front of a screen (television, computer, tablet, phone, based on the survey’s sample mean, which value could be the population mean? 2.3 hours 27.4 hours 75.3 hours 41.5 hours

Rewrite the following quadratic functions in intercept or factored form. show your work. f(x) = 3x^2 - 12