The angle at the circumference in a semi-circle is 90°. Angle STU = 90° Angles in a triangle add up to 180°. The angle on a straight line is 180°. The angle VOY = 180°. The angle at the ...

THIS work of Prof. Smith's has a “very practical purpose,” viz, “to present in simple and intelligible form a body of geometric doctrine, acquaintance with which may fairly be demanded of ...