Question

Which relationship in the triangle must be true? sin(b) = sin(a) sin(b) = cos(90 –

b.cos(b) = sin(180 –
b.cos(b) = cos(a)?

Answer 1

the answer is B

Explanation:

Answer 2

Assuming angle a and angle b are not equal and the given triangle is a right triangle .

Let's see cos(90-b)

Here we use the formula of cos(A-B)=cos A cos B -sin A sin B

And on using this formula,we will get

cos(90-b)= cos 90 cos b + sin 90 sin b

Value of cos 90 = 0 and sin 90 =1 , And on using these values, we will get

cos(90-b) = (0) cos (b) + (1) sin (b)

cos(90-b) = 0 + sin (b)

cos(90-b) =sin(b)

As we see that on using the formula, we are getting cos(90-b)= sin b .

So the correct option is cos(90-b)= sin b