
Yefim S. answered 12/01/22
Math Tutor with Experience
sinβ + 1 = 2cos2β; sinβ + 1 = 2 - 4sin2β; 4sin2β + sinβ - 1 = 0; sinβ = (- 1 ± √17)/8
sinβ = (- 1 + √17)/8; sin-1((- 1 + √17))/8) = 23°; or β = 180° 23° = 157˜.
sinβ = (- 1 - ; √17)/8; β = 180° + sin-1(1 + √17)/8) = 220˜ or β = 360° - sin°((1 + √17)/8) = 320°