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AS Core 2 Trigonometry. Created by : Ali V Ali. Measuring Angles : In Degrees or Radians. . 360 o. The angle, , can be measured in degrees. This represents the turn required to move from one line to the other in the direction shown.
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AS Core 2Trigonometry Created by : Ali V Ali
Measuring Angles : In Degrees or Radians 360o The angle, , can be measured in degrees. This represents the turn required to move from one line to the other in the direction shown. This turn is measured in degrees. Degrees are a unit measuring turning where 360o is a full turn.
Radians is another measure for angles. This time you represent the angle as the distance point A moves around the circumference of an imaginary circle. A If we imagine a circle of radius 1 unit, then a full turn would be a full circle and the point A moves would be the same as the circumference of the circle • 360o = 2 radians (or 2 c) • 1o = 2 c 360o • 1 c = 360o 2
Uses of radians L Here we have a sector draw with angle . This sector has an arc length of L and an area of A. r Area,A r In radians … In degrees … Length of arc, L L = (2 r) 360o Area of sector, A A = (r 2) 360o L = (2 r) = r 2 A = (r2) = ½ r2 2
Hypotenuse Opposite Adjacent sine = opposite ÷ hypotenuse cosine = adjacent ÷ hypotenuse tangent = opposite ÷ adjacent
Some Standard Solutions … x 0o 45o x Hypotenuse = Adjacent Opposite = 0 sin 0o = 0 cos 0o = 1 tan 0o = 0 Adjacent = Opposite = x Hypotenuse = x2 sin 45o = 1/2 cos 45o = 1/2 tan 45o = 1 30o 60o x x 60o 60o 90o x For 30o Hypotenuse = x Opposite = x Adjacent = x 3 2 2 sin 30o = 1 cos 30o = 3 tan 30o = 1 2 23 For 60o Hypotenuse = x Adjacent = x Opposite = x 3 2 2 sin 60o = 3 cos 60o = 1 tan 60o = 3 2 2 Hypotenuse = Opposite Adjacent = 0 sin 90o = 1 cos 90o = 0 tan 90o = undefined
90o 90o Opposite = + Adjacent = + Opposite = + Adjacent = - 180o 0o 180o 0o 270o 270o 90o 90o Opposite = - Adjacent = - Opposite = - Adjacent = + 180o 0o 180o 0o 270o 270o
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Solve : sin x = 0.5 for the range 0 ≤ x ≤ 360o x = arcsin 0.5 = 30o but sin is positive in two quadrants so x = 30o or (180 – 30)=150o
Solve : sin x = 0.5 for the range 0 ≤ x ≤ 360o x = arcsin 0.5 = 30o but sin is positive in two quadrants so x = 30o or (180 – 30)=150o