Find the angle in radian though which a pendulum swings if its length is 75 cm and the tip describes an arc of length
(i) 10 cm (ii) 15 cm (iii) 21 cm
We know that in a circle of radius r unit, if an arc of length / unit subtends an angle θ radian at the centre, then .
\(θ=\frac{i}{r}\)
It is given that r = 75 cm
(i) Here, l = 10 cm
\(θ=\frac{10}{75}\,radian=\frac{2}{15}\,radian\)
(ii) Here, l = 15 cm
\(θ=\frac{15}{75}\,radian=\frac{1}{5}\,radian\)
(iii) Here, l = 21 cm
\(θ=\frac{21}{75}\,radian=\frac{7}{25}\,radian\)
The graph shown below depicts:
The relationship between the sides and angles of a right-angle triangle is described by trigonometry functions, sometimes known as circular functions. These trigonometric functions derive the relationship between the angles and sides of a triangle. In trigonometry, there are three primary functions of sine (sin), cosine (cos), tangent (tan). The other three main functions can be derived from the primary functions as cotangent (cot), secant (sec), and cosecant (cosec).
sin x = a/h
cos x = b/h
tan x = a/b
Tan x can also be represented as sin x/cos x
sec x = 1/cosx = h/b
cosec x = 1/sinx = h/a
cot x = 1/tan x = b/a