In isosceles right triangle ABC, point D is on hypotenuse line BC such that line AD is an altitude of triangle ABC and DC = 5. What is the

Since it is an isoc right triangle the two legs are the same length (and the angles of the triangle are 90 45 45)       Line DC = 5    Line BD = 5    AND Line AD will equal 5   

Area of smaller triangle = 1/2 (5)(5)        Total area will be the sum of the two small triangles (which are identical)    2 x 1/2 5 x 5 = 25 units^2