4+cosa+tg^2a если cosa=1/2

Cosα = 1/2.

---

(4+cosα + tq²α) - ?

4+cosα + tq²α = 4+cosα + tq²α = 4+cosα + (1-cos²α) / cos²α =

4+1/2 + (1 - (1/2) ²) / (1/2) ² = 4+1/2 + (1-1/4) / (1/4) = 4+1/2 + (3/4) / (1/4) = 4+1/2 + 3 = 7,5.