The national cost C in billions of dollars for dental services can be modeled by the linear equation C=285n+ 30.52, where n is the number of years since 1990. What would be the cost in billions of dollars in 2014? Assume the model remains accurate. In 2014, the cost would be billion dollars. (Type an integer or decimal rounded to two decimal places as needed.)

Given: abcd is a square. prove: ac ? bd. we are given that abcd is a square. if we consider triangle aeb and triangle aed, we see that side is congruent to side ad because sides of a square are congruent. we know that side ae is congruent to side ae by using the . finally, we know that side de is congruent to side because the diagonals of a square bisect each other. therefore, triangle aeb is congruent to triangle aed by congruency. we see that angle aed and angle aeb are a linear pair, and congruent by cpctc. thus, the measure of these angles will be 90°, and diagonal ac is perpendicular to diagonal bd by the .