Answer: 5/8
Step-by-step explanation:
Pythagorean theorem is

and using that sin is opposite/hypotenuse, you can find the third side of the triangle.

now you know adjacent is 60, so cos=60/61
Answer:
1375
Step-by-step explanation:
The answer would be : A parallelogram with congruent sides does NOT guarantee that a quadrilateral is a rectangle