If sinθ = A, find cos(π/2-θ)

(using trigonometric identities to fine the value)

Cos(π/2 - θ) = A

Step-by-step explanation:

We know that:

Sin(θ) = A

And we want to find the value of Cos(π/2 - θ)

Here we can use the cosine relationship:

Cos(a - b) = Cos(a)*Cos(b) + Sin(A)*Sin(B)

Then:

Cos(π/2 - θ) = Cos(π/2)*Cos(θ ) + Sin(π/2)*Sin(θ)

We know that:

Cos(π/2) = 0

Sin(π/2) = 1

Then:

Cos(π/2 - θ) = Cos(π/2)*Cos(θ ) + Sin(π/2)*Sin(θ) = 0*Cos(θ ) + 1*Sin(θ)

                    = 1*Sin(θ) = A

Cos(π/2 - θ) = A

i think it is everything has to equal 180 so, if i correct 4=c. 6=d. 8=a. 7=b. and the last question would be c. because they are parallel lines and they are congruent.

step-by-step explanation:

the reason everything has to equal to 180 is because that is how it works. i'm guessing that is its rule. 4 and 8 are congruent and parallel so, that would be 30+30 because they have the same number. it would equal 60. 6 and 7 are congruent and parallel so, that would be 30+30 because they have the same number. it would equal 60. 60+60 is 180. so, now you have your answer

false

step-by-step explanation:

false.   two legs of the trapezoid would be congruent, but the other two would not.   were all the legs congruent, then we'd have a square; were the 2 shorter sides congruent and the 2 longer sides also congruent, we'd have a rectangle.