6 12 points SPreCalc6 73031 Simplify the expression by using

6. -12 points SPreCalc6 7.3.031 Simplify the expression by using a Double-Angle Formula or a Half-Angle Formula. (a) cos2 34 sin2 34 (b) cos2 78-sin2 7 7. -12 points SPreCalc6 7.3.043 Write the given expression as an algebraic expression in x. sin(2 tan-1 x) -12 points SPreCalc6 7.3.046 Write the given expression as an algebraic expression in x. cos(2 sin-1x)

Solution

6. a. cos²34 -sin²34

This is of the form cos²A- sin²A= cos(2A)

So we get cos²34 -sin²34=cos(2*34)= cos 68

b. cos²7theta -sin²7theta = cos(2*7theta)=cos(14 theta)