The left side can be condensed as a squared binomial:
Since 1 dekameter equals 10 meters and he has 3, he has a total of 30 meters.
That equals 30, 1 piece meters.
the answer is the first one A
A right angled triangle can be formed from the given scenario as shown below in the figure:
We have a perpendicular(opposite side), the measure of angle and we are interested in finding the hypotenuse.
sine of the angle relates its perpendicular side to hypotenuse as:
sin(x) = perpendicular/hypotenuse
⇒
Hypotenuse = Perpendicular/sin(x) = 13/sin(70) = 13.8 feet
This means, the length of the ladder is 13.8 feet, rounded to nearest tenth.