Since you’re already given one of the sides of the triangles as well as the triangle’s hypotenuse, you’ll want to find the third side to find the area.
To find the third side length, we’ll use the Pythagorean Theorem:
a^2 + b^2 = c^2
“a” and “b” can be used interchangeably, so we can substitute the known side length of 7 cm into “a”. 25 cm substitutes for “c” since it’s the hypotenuse.
(25)^2 - (7)^2 = c^2
c = 24
Area of triangle = (1/2)bh, where “b” and “h” are interchangeable.
Area of triangle = (1/2)(24)(7) = 84 cm^2