Which relationship in the triangle must be true? A
c
b
C
B
а
sin(B) = sin(A)
sin(B) = cos(90 - B)
COS(B) = sin(180 - B)
cos(B) = (A)

sin(B) = cos(90 - B).

Step-by-step explanation:

To answer this question, you must understand SOH CAH TOA.

SOH = Sine; Opposite divided by Hypotenuse

CAH = Cosine; Adjacent divided by Hypotenuse

TOA = Tangent; Opposite divided by Adjacent

I roughly drew a triangle for reference. Let's say we have a 3-4-5 triangle.

As you can see, sin(b) does not equal sin(a). To get the sine of an angle, you would do opposite over hypotenuse. For angle B, that would be 3/5, while for angle A, that would be 4/5.

As stated above, sin(B) is 3/5. Now, if you did cos(90 - B), it would be the same thing as cos(A). This is because the triangle is a right triangle. Since a triangle has 180 degrees, and one angle is a right triangle, the other two angles will add up to be 90 degrees. So, 90 - B = A. cos(A) is the same thing as adjacent over hypotenuse, which is 3/5. So, sin(B) = cos(90 - B) must be true.

Let's just check the others to make sure they are false.

cos(B) = 4/5.

sin(180 - B) is basically the same thing as sin(A + C), which is definitely NOT 4/5.

cos(B) = 4/5, which is NOT the same as A.

So, your answer is sin(B) = cos(90 - B).

Hope this helps!

me i beg !

step-by-step explanation:

the entire expression should be subtracted from 30. to subtract the quantity, distribute the negative sign, which changes the signs on the terms. so, the –2 changes to positive and gets added to 30 instead of subtracted from it.

hope this ! ^w^