to calculate an area of a rectangle, use the formula a=l*w. we know the width is half as long as the length. so w = 1/2 l.
so the area is
if the area is 18 then substitute a =18.
since length cannot be negative, then l=6.
the width is 1/2 l so w = 1/2 (6) = 3.
hello from mrbilldoesmath!
the attachment shows a right triangle where arcsin(@) = 1/4. (the arcsin means find the angle whose sine is 1/4 as is done in the triangle.) the missing side, sqrt(15), shown in red, was determined by the pythagorean theorem.
then cos(@) = cos(arcsin(1/4)) = sqrt(15)/4
∠a = 40°
∠c = 32°
inscribed angles that intercept the same arc have the same measure.
∠a intercepts the same arc (cd) as ∠b, so has the same measure, 40°.
∠c intercepts the same arc (ab) as ∠d, so has the same measure, 32°.