## Intermediate Algebra (6th Edition)

We know that the angles of a triangle must add up to 180°. We are given that the angles of this triangle are 57°, 90°, and x°. Therefore, we can sum these up and set the sum equal to 180° to solve for the unknown angle. $57+90+x=147+x=180$ Subtract 147 from both sides. $x=33°$ Recall that the square symbol indicates a right angle, which is equal to 90°.