Without using trigonometric tables, evaluate the following (6 to 10): 6. (i) cos2 26o + cos 64o sin 26o + (tan 36o/ cot 54o) (ii) (sec 17o/ cosec 73o) + (tan 68o/ cot 22o) + cos2 44o + cos2 46o

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deepaksoniGuru

Asked: March 15, 20212021-03-15T20:48:39+05:30 2021-03-15T20:48:39+05:30In: ICSE

Without using trigonometric tables, evaluate the following (6 to 10): 6. (i) cos2 26o + cos 64o sin 26o + (tan 36o/ cot 54o) (ii) (sec 17o/ cosec 73o) + (tan 68o/ cot 22o) + cos2 44o + cos2 46o

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This question is from the Book- ML Aggarwal
Board- ICSE
Publication- Avichal
Chapter- Trigonometric Identities
Chapter number-18
This ques has been asked in 2012 exam. So it is very important ques for this point of view.

Without using trigonometric tables, evaluate the following (6 to 10):

6. (i) cos² 26^o + cos 64^o sin 26^o + (tan 36^o/ cot 54^o)

(ii) (sec 17^o/ cosec 73^o) + (tan 68^o/ cot 22^o) + cos² 44^o + cos² 46^o

Class10th ML Aggarwal, ICSE board

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AAREKH · Answer 1 · 2021-03-15T20:49:51+05:30

AAREKH Guru

2021-03-15T20:49:51+05:30Added an answer on March 15, 2021 at 8:49 pm

Solution:

Given,

(i) cos² 26^o + cos 64^o sin 26^o + (tan 36^o/ cot 54^o)

= cos² 26^o + cos (90^o – 16^o) sin 26^o + [tan 36^o/ cot (90^o – 54^o)]

= [cos² 26^o + sin² 26^o] + (tan 36^o/ tan 36^o)

= 1 + 1 = 2

(ii) (sec 17^o/ cosec 73^o) + (tan 68^o/ cot 22^o) + cos² 44^o + cos² 46^o

= [sec 17^o/ cosec (90^o – 73^o)] + [(tan 90^o– 22^o)/ cot 22^o] + cos² (90^o – 44^o) + cos² 46^o

= [sec 17^o/ sec 17^o] + [cot 22^o/ cot 22^o] + [sin² 46^o + cos² 46^o]

= 1 + 1 + 1

= 3

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Without using trigonometric tables, evaluate the following (6 to 10): 6. (i) cos2 26o + cos 64o sin 26o + (tan 36o/ cot 54o) (ii) (sec 17o/ cosec 73o) + (tan 68o/ cot 22o) + cos2 44o + cos2 46o

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