further pure 1

2.(a)Write down the t-formula for sin x.
(1)
(b)Using the answer to part (a),
(i)find the exact value of sin x when

(ii)show that
cos x =
(4)
(c)Use the t-formulae to solve for 0 < 𝜃 ⩽ 360°
7sin 𝜃 + 9cos 𝜃 + 3 = 0
giving your answers to one decimal place.
(4)
anyone got any idea how to do part bii i have tried using cos^2x=1-sin^2x but not getting anywhere
I’ll attach a picture of the question

2.(a)Write down the t-formula for sin x.
(1)
(b)Using the answer to part (a),
(i)find the exact value of sin x when

(ii)show that
cos x =
(4)
(c)Use the t-formulae to solve for 0 < 𝜃 ⩽ 360°
7sin 𝜃 + 9cos 𝜃 + 3 = 0
giving your answers to one decimal place.
(4)
anyone got any idea how to do part bii i have tried using cos^2x=1-sin^2x but not getting anywhere
I’ll attach a picture of the question

Your method for b(ii) should work. Feel free to post your working if stuck. Alternatively, since you've completed part (a) you can draw a right angled triangle with the known lengths of the opposite and hypotenuse in terms of t, and work out the adjacent side using Pythagoras.