Question #b619a

1 Answer
Feb 3, 2018

#theta=149.16^@, 210.84^@#

Explanation:

All angles to 2 d.p in degrees.

#0^@ < theta<=360^@#
#costheta=-0.8586#

Use our calculator to find one value:

#theta=cos^-1(-0.8586)#
#theta=149.16^@#

We also know that #costheta=cos(360^@-theta)# You can verify this using the cos graph.

enter image source here
#cos30=cos330# and #cos60=cos300#

#:. cos149.16=cos(360-149.16)#

#theta=149.16^@, 210.84^@#