Jul 16, 2015 · Solve triangle, knowing A = 43, a = 12.2, b = 14 Anser: B = 51.30 Apply the trig identity: sin a/A = sin B/b Find angle B: sin B/b = sin A/a --> sin B = (14 (0.68))/12.2 ==.78 --> --> B = 51.30 deg
Questions and Videos on Half-Angle Identities, within Trigonometry
simplify (sin x - cos x)(sin x + cos x) Ans: -cos 2x Apply the trig identity: cos 2x = (cos^2 x - sin^2 x) (sin x - cos x)(sin x + cos x) = sin^2 x - cos^2 x .
For triangle angles, between 0 and 180^circ, the cosine is positive for acute angles, zero for a right angle, and negative for obtuse angles, bigger than 90^circ. So the negative cosine tells us one.
