Question

Solve the equation 3tan(2x+15°)=4 for 0°is less than equal to x and 180° is greater than equal to x.

Answer 1

Answer:

$3tan(2x+15)=4\\or, \frac{tan2x+tan15}{1-tan2x.tan15} =\frac{4}{3}\\or, 3tan2x+3tan15=4-4tan2x.tan15 \\or, 3tan2x+4tan2x.tan15=4-3tan15\\or, tan2x(3+4tan15) = 4-3tan15\\or, tan2x = \frac{4-3tan15}{3+4tan15}\\or, 2x =tan^{-1}(\frac{4-3tan15}{3+4tan15})\\or, x = \frac{tan^{-1}(\frac{4-3tan15}{3+4tan15})}{2} = 19.06505118 (approximate)$$Note: tan30 = \frac{2tan15}{1-tan^{2}15}\\or, \frac{1}{\sqrt{3} } = \frac{2tan15}{1-tan^{2}15}\\or, 1-tan^{2}15 = 2\sqrt{3}tan15\\or, tan^{2}15+2\sqrt{3}tan15-1=0\\Solve~using~the~quadratic~formula~to~get~tan15^o=2-\sqrt{3}.$