Practice problem
If csc(x)=7\csc(x)=7csc(x)=7 and 90∘<x<180∘90^{\circ}<x<180^{\circ}90∘<x<180∘, then find the exact value for cos(x2)\cos(\frac x2)cos(2x)
−7−4514-\sqrt{\frac{7-4\sqrt5}{14}}−147−45
7−4514\sqrt{\frac{7-4\sqrt5}{14}}147−45
−7−4314-\sqrt{\frac{7-4\sqrt3}{14}}−147−43
7−4314\sqrt{\frac{7-4\sqrt3}{14}}147−43
Type a concept, like “slope” or “photosynthesis”.