If 20° + x is an acute angle and cos(20° + x) = sin 60°, then find the value of x.

If θ is an acute angle and sin θ = cos θ, find the value of θ and hence, find the value of 2 tan² θ + sin² θ - 1.

From the adjoining figure, find

(i) tan x°

(ii) x

(iii) cos x°

(iv) use sin x° to find y.