Sin 3pi/4 is angle 135 degrees or 45 degrees below 180 degrees. Hence it's opposite side is 1 and adjacent is 1, implying the hypothenus is sqrt(2). Hence
Sin 3pi/4 = 1/sqrt(2). Now multiply by sqrt(2)/sqrt(2) to get:
[1/sqrt(2).] * [sqrt(2)/sqrt(2)] = sqrt2)/2
The answer is...B. ways of maintaining relationships
A = 2lw + 2lh + 2wh
A = 2(43)(19) + 2(43)(35) + 2(19)(35)
A = 2(817) + 2(1505) + 2(665)
A = 1634 + 3010 + 1330
A = 5974in²