Answer:
1633.3 meters
Explanation:
-Given the angle of depression is 31°, and the plane's height above the ground is 1400m.
-We use the Law of Sines to determine the distance between the plane and the rock.
-The angle of elevation from the rock to the plane is(corresponds to the plane's altitude):
![\angle elevation=90-31\\=51\textdegree](https://img.qammunity.org/2021/formulas/mathematics/high-school/tcla1glg88qojm3nojs24jvjavyqyn9kbk.png)
#Now, using Sine Law;
![(a)/(Sin \A)=(b)/(Sin \ B)\\\\\\(1400)/(Sin \ 59)=(d)/(Sin \ 90)\\\\\\\\=1633.287\approx 1633.3\ m](https://img.qammunity.org/2021/formulas/mathematics/high-school/u836tyy53m97qrkmnrwo92ltuglbqrt4ry.png)
Hence, the direct distance between the plane and the rock is 1633.3 meters