The explanation is t<span>he straight </span>angle<span> is the only type of </span>angle formed by two opposite rays<span>. All other </span>angles formed by two rays<span> are less than </span>180<span> degrees. Acute </span>angles<span> are between zero and 90 degrees. A right </span>angle<span>, with one </span>ray<span> perpendicular to another, is 90 degrees.
