In the given figure of ΔPQR, ∠ P = θ° and ∠ R = ϕ°. Find

a.


b.


c. Cosθ



Δ PQR is a right - angled triangle


By Pythagoras theorem, (hypotenuse)2 = (perpendicular)2 + (base)2


∴PR2 = RQ2 + PQ2


= (x + 2)2 = x2 + PQ2


= x2 + 4 + 4x = x2 + PQ2


PQ2 = 4 + 4x


→ PQ = 2


a. cotϕ = RQ/PQ =


∴ × =


= x/2


b. tanθ = RQ/PQ =


∴ =


= x×


= x2/2


c. cosθ = PQ/RP =


33
1