trig

RPQ is supplemental to RPS

And the sines of supplemental angles are equal

Thus...... sin RPQ = sin RPS = 7/25

And since RPS is obtuse, the cosine of this angle =  - sqrt[ 25^2 - 7^2 ] / 25 =

- sqrt [ 625 - 49 ] / 25 =

- sqrt [ 576] / 25 =

-24 / 25

cos(180°-θ) = - cos θ            & sin(180°-θ) = sin θ

So cos of rps = - cos rpq

1-sin^2 = cos^2

1-(7/25)^2 = cos^2

.96 =cos ^2

cos = .96                            - cos = - .96   (-24/25)