We know that sin(θ)=cos(90−θ). Using this property, we can rewrite the given equation. sin(5x2)=cos(2x+6) cos(90−5x2)=cos(2x+6) Since the cosine values are equal, we can equate the angles:
90−5x2=2x+6 Rearranging the terms, we get a quadratic equation:
5x2+2x−84=0 We can solve this quadratic equation using the quadratic formula:
x=2a−b±b2−4ac where a=5, b=2, and c=−84. x=2(5)−2±22−4(5)(−84) x=10−2±4+1680 x=10−2±1684 x=10−2±2421 x=5−1±421 So the two possible solutions are:
x=5−1+421 and x=5−1−421 Approximating 421≈20.518 x≈5−1+20.518≈519.518≈3.9036 x≈5−1−20.518≈5−21.518≈−4.3036