Q. 4 A3.9( 36 Votes )

# In ∆ABC, right angled at B, AB = 24 cm, BC = 7 cm. Determinea. sin A, cos Ab. sin C, cos C

(i)

(a) sin A

We know that,

So, here θ = A

Side opposite to A = BC = 7

Hypotenuse = AC = ?

Firstly we have to find the value of AC.

So, we can find the value of AC with the help of Pythagoras theorem.

According to Pythagoras theorem,

(Hypotenuse)2 = (Base)2 + (Perpendicular)2

(AB)2 + (BC)2 = (AC)2

(24)2 + (7)2 = (AC)2

576 + 49 = (AC)2

(AC)2 = 625

AC =625

AC =±25

But side AC can’t be negative. So, AC = 25cm

Now, BC = 7 and AC = 25

So,

Cos A

We know that,

So, here θ = A

Side adjacent to A = AB = 24

Hypotenuse = AC = 25

So,

(b) sin C

We know that,

So, here θ = C

The side opposite to C = AB = 24

Hypotenuse = AC = 25

So,

Cos C

We know that,

So, here θ = C

Side adjacent to C = BC = 7

Hypotenuse = AC = 25

So,

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