Let AB extended intersect DC extended at point E <span>We now have right triangle BEC with E = 90 degrees </span>
<span>For triangle BEC: </span> <span>Exterior angle at E = 90 </span> <span>Exterior angle at C = 148 (given) </span> <span>Exterior angle of all polygons add up to 360 degrees </span> <span>Exterior angle at B = 360−148−90 = 122 </span>
FOIL method First: u squared times u squared equals to u to the fourth. Outer and Inner: 8u squared + u squared equal 9u squared. Remember, the exponents don't change when adding! Last: 8 times 1 equals 8