Question

cos²Φ+sinΦ+1=0
solve for Φ

Hint: use identity formula sin²Φ+cos²Φ=1​

Answer 1

Step-by-step explanation:

${ \cos( \alpha ) }^{2} + \sin( \alpha ) + 1 = 0 \\ 1 - { \sin( \alpha ) }^{2} + \sin( \alpha ) + 1 = 0 \\ { \sin( \alpha ) }^{2} - \sin( \alpha ) - 2 = 0 \\ \sin( \alpha ) = - 1 \: or \: \sin( \alpha = 2) \\ so \: \: \\ \sin( \alpha ) = - 1 \\ \alpha = 3 \frac{\pi}{2}$