Third choice is correct hope I helped:3
Answer:
option B. 
Step-by-step explanation:
we know that
1) The two diagonals of a rhombus are perpendicular
2) The sum of the interior angles in any triangle must be equal to 180 degrees
Let
O ----> the intersection point of the diagonals of the rhombus
In the right triangle OAD

solve for x




Given:
In triangle OPQ, o = 700 cm, p = 840 cm and q=620 cm.
To find:
The measure of angle P.
Solution:
According to the Law of Cosines:

Using Law of Cosines in triangle OPQ, we get




On further simplification, we get




Therefore, the measure of angle P is 79 degrees.