Page 52 - DMTH201_Basic Mathematics-1

Unit 2: Trigonometric Functions-II

2
(iii) 1 + tan x = sec x Notes
2
2
(iv) 1 + cot x = cosec x
2
(v) Sum of cosine of two angles
cos (x + y) = cos x cos y – sin x sin y
(vi) Difference of cosine of two angles
cos (x – y) = cos x cos y + sin x sin y
(vii) Sum of sines of two angles

sin (x + y) = sin x cos y + cos x sin y
(viii) Difference of sines of two angles
sin (x – y) = sin x cos y – cos x sin y

2.8 Self Assessment

1. The exact value of cos 75°
(a)
(b) 1

(c)

(d)
2. Value of 3 tan² (B/2) −1 = 0

(a)

(b)
(c) 1/2
(d)
3. Vale of sin 2A

(a) 1/2
(b)

(c)

(d)
4. Sin 120° − cos 150° is equals to

(a)
(b)
(c)

(d)

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