Answer:
about 100 cm²
Explanation:
The side length of the rhombus is 1/4 of the perimeter so is 10 cm. The length of half of the other diagonal will be the length of the leg of a right triangle with hypotenuse 10 and leg 7 (half the given diagonal).
d= √(10² -7²) = √51
Then the area of the rhombus is the product of this and the given diagonal:
A = (14 cm)(√51 cm) ≈ 99.98 cm²
The area of the rhombus is about 100 cm².