Question

In ΔABC, ∠C is a right angle. If cosB = 5/13, what is sinA?

Answer 1

The correct answer is Sin A =5/13

Explanation:

Trigonometric ratio:-

Sin∅ = opposite side /Hypotenuse

cos∅ = Adjacent side/ Hypotenuse

From the given figure, we get

Triangle ABC is a right angled triangle,

<C = 90°

To find sinA

Cos B = Adjacent side/ Hypotenuse = 5/13

Adjacent side = 5 and Hypotenuse = 13

Adjacent side of angle B = Opposite side of angle A

Therefore,

Sin A = opposite side /Hypotenuse = 5/13

The correct answer is Sin A =5/13

Answer 2

The value of sinA is
`(5)/(13)`.

Explanation:

ΔABC

Base = b = BC

Hypotenuse = h = AB

Perpendicular = p = AC

`\cos B=(b)/(h)=(BC)/(AB)=(5)/(13)`

If we rotate the triangle in such a way so that base changes from BC to AC, then:

Base = b = AC

Hypotenuse = h = AB

Perpendicular = p = BC

`\sin A=(p)/(h)=(BC)/(AB)=(5)/(13)`

The value of sinA is
`(5)/(13)`.