Point 1 of 11 — Unit 4: Trigonometry — Directed Angles, Functions, Related Angles and GraphsQuestion bank: 0 questions (0 with pictures)
01 4-1 The directed angle and its standard position
Adirected angle is generated by a ray rotating about its endpoint from an initial sideto aterminal side: counter-clockwise is positive, clockwise is negative.
The angle is instandard position when its vertex is at the origin and its initial side lies along the positive x-axis.
The quadrant of the angle is the quadrant in which its terminal side lies: 0–90° first, 90–180° second, 180–270° third, 270–360° fourth.
Angles whose sides are parallel to the axes (0°, 90°, 180°, 270°, 360°) are quadrantaland belong to no quadrant.
Coterminal angles and revolutions
Coterminal angles share the initial and terminal sides and differ by a multiple of 360°: θ + 360°k, k ∈ ℤ.
Half a turn = 180°, one turn = 360°, two and a quarter turns = 810°; add 360° for every full turn.
To name the angle from a figure: measure the rotation from the positive x-axis in the given direction, keeping the sign.
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