# In ∆PQR, ∠Q is a right angle PQ = 3, QR = 4. If ∠P=α and ∠R=β, then find the values of(i) sin α (ii) cos α(iii) tan α (iv) sin β(v) cos β (vi) tan β Given : PQ = 3, QR = 4

(PQ)2 + (QR)2 = (PR)2

(3)2 + (4)2 = (PR)2

9 + 16 = (PR)2

(PR)2 = 25

PR =25

PR =±5

But side PR can’t be negative. So, PR = 5

(i) sin α

We know that, Here, θ = α

The side opposite to angle α = QR =4

Hypotenuse = PR =5

So, (ii) cos α

We know that, Here, θ = α

The side adjacent to angle α = PQ =3

Hypotenuse = PR =5

So, (iii) tan α

We know that, Here, θ = α

Side opposite to angle α = QR =4

Side adjacent to angle α = PQ =3

So, (iv) sin β

We know that, Here, θ = β

The side opposite to angle β = PQ =3

Hypotenuse = PR =5

So, (v) cos β

We know that, Here, θ = β

Side adjacent to angle β = QR =4

Hypotenuse = PR =5

So, (vi) tan β

We know that, Here, θ = β

Side opposite to angle β = PQ =3

Side adjacent to angle β = QR =4

So, Rate this question :

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