Question

Without using trigonometric table, evaluate the following:

tan10º tan15º tan60º tan75º tan80º​

Answer 1

Answer:

(i) L.H.S. = tan 10˚ tan 15˚ tan 75˚ tan 80˚

= tan 10˚ tan 15˚ tan (90˚ – 15˚) tan(90˚ – 10˚)

= tan 10˚ tan 15˚ cot 15˚ cot 10˚

1/cot10˚ × 1/cot 15˚ × cot 15˚ × cot 10˚

= 1 = R.H.S.

Hence proved.

(ii) L.H.S. = cos 1˚ cos 2˚ cos 3˚ …..cos 180˚

= cos1˚ cos2˚ cos 3˚ …..cos 89˚ cos 90˚ ….cos 180˚

= cos 1˚ cos 2˚ cos 3˚ ….cos 89˚ × 0 × cos 91˚ ….cos 180˚

= 0 = R.H.S.

Hence proved.

Related questions

0

votes

1

answer

Without using table evaluate 2 tan 53˚/cot 37˚ – cot 80˚/tan 10˚

asked Mar 27, 2019 in Class X Maths by priya12 (-12,631 points)

trigonometry

0

votes

1

answer

Without using trigonometric table prove that (cos2 26˚ + cos 64˚ sin 26˚ + tan 36˚/cot 54˚ = 2

asked Mar 30, 2019 in Class X Maths by muskan15 (-3,443 points)

trigonometry

0

votes

1

answer

Without using tables evaluate : 3 cos 80˚ Cosec 10˚ + 2 sin 59˚ sec 31˚

asked Mar 27, 2019 in Class X Maths by navnit40 (-4,939 points)

trigonometry

0

votes

1

answer

Without using trigonometric tables, evaluate sin2 34˚ + sin2 56˚ + 2 tan 18˚ tan 72˚ – cot2 30˚

asked Mar 27, 2019 in Class X Maths by navnit40 (-4,939 points)

trigonometry

0

votes

1

answer

Using trigonometric tables evaluate the following : tan 25˚46’ + cot 45˚25’

asked Mar 27, 2019 in Class X Maths by aditya23 (-2,145 points)

trigonometry

0

votes

1

answer

Without using trigonometric tables, find the value of (sin 72˚ + cos 18˚)(sin 72˚ – cos 18˚)

asked Mar 27, 2019 in Class X Maths by navnit40 (-4,939 points)

trigonometry

0

votes

1

answer

Prove that sin2 5˚ + sin2 10˚…….. sin2 85˚ + sin2 90˚ = 9.1/2

asked Mar 31, 2019 in Class X Maths by navnit40 (-4,939 points)

trigonometry

0

votes

1

answer

Prove that : (i) 1/(sec θ – tan θ) = sec θ + tan θ

asked Mar 31, 2019 in Class X Maths by priya12 (-12,631 points)

trigonometry

0

votes

1

answer

Prove that : (sec θ – tan θ)2 = (1 - sin θ/1 + sin θ)

asked Mar 31, 2019 in Class X Maths by priya12 (-12,631 points)

trigonometry

0

votes

1

answer

Prove that (tan 20˚/cosec 70˚)2 + (cot 20˚/sec 70˚)2 = 1.

asked Mar 30, 2019 in Class X Maths by aditya23 (-2,145 points)

trigonometry

All categories

Biology(241)

Board Exams(195)

Class XII Business Studies(580)

Class XII Accountancy(22)

Class XII Economics(25)

Class XII Psychology(12)

Class XII Political Science(12)

Class XII Physical Education(9)

Class XII English(225)

Class XII Biology(756)

Class XII Chemistry(248)

Class XII Physics(367)

Class XII Maths(502)

Class XI Business Studies(1.3k)

Class XI Accountancy(29)

Class XI Economics(37)

Class XI Psychology(5)

Class XI Political Science(63)

Class XI Physical Education(26)

Class XI English(62)

Class XI Biology(2.9k)

Class XI Chemistry(436)

Class XI Physics(409)

Class XI Maths(513)

Class X Social Science(8.8k)

Class X Science(6.7k)

Class X Maths(1.8k)

Class X English(1.1k)

Class X Hindi(598)

Class X Computer(12)

Class IX Social Science(3.2k)

Class IX Science(1.3k)

Class IX Maths(1.8k)

Class IX English(1.4k)

Class IX Hindi(270)

Class IX Computer(28)

Class VIII Social Science(151)

Class VIII Science(833)

Class VIII Maths(1.0k)

Class VIII English(73)

Class VIII Hindi(95)

Class VIII Computer(5)

Class VII Maths(872)

Class VII Science(726)

Class VII English(10)

Class VII Social Science(29)

Class VII Hindi(6)

Class VII Computer(6)

Class VI Maths(1.0k)

Class VI Social Science(8)

Class VI Science(505)

Class VI English(3)

Class VI Hindi(5)

Class VI Computer(5)

Sanskrit(1)

Geography(14)

History(14)

Political Science(11)

Who is Who(0)

Other(3.2k)

Exams(5)

Science(1.6k)

Important Questions(3.9k)

Entertainment(7)

Categories

All categories

Biology(241)

Board Exams(195)

Class XII Business Studies(580)

Class XII Accountancy(22)

Class XII Economics(25)

Class XII Psychology(12)

Class XII Political Science(12)

Class XII Physical Education(9)

Class XII English(225)

Class XII Biology(756)

Class XII Chemistry(248)

Class XII Physics(367)

Class XII Maths(502)

Class XI Business Studies(1.3k)

Class XI Accountancy(29)

Class XI Economics(37)

Class XI Psychology(5)

Class XI Political Science(63)

Class XI Physical Education(26)

Class XI English(62)

Class XI Biology(2.9k)

Class XI Chemistry(436)

Class XI Physics(409)

Class XI Maths(513)

Class X Social Science(8.8k)

Class X Science(6.7k)

Class X Maths(1.8k)

Class X English(1.1k)

Class X Hindi(598)

Class X Computer(12)

Class IX Social Science(3.2k)

Class IX Science(1.3k)

Class IX Maths(1.8k)

Class IX English(1.4k)

Class IX Hindi(270)

Class IX Computer(28)

Class VIII Social Science(151)

Class VIII Science(833)

Class VIII Maths(1.0k)

Class VIII English(73)

Class VIII Hindi(95)

Class VIII Computer(5)

Class VII Maths(872)

Class VII Science(726)

Class VII English(10)

Class VII Social Science(29)

Class VII Hindi(6)

Class VII Computer(6)

Class VI Maths(1.0k)

Class VI Social Science(8)

Class VI Science(505)

Class VI English(3)

Class VI Hindi(5)

Class VI Computer(5)

Sanskrit(1)

Geography(14)

History(14)

Political Science(11)

Who is Who(0)

Other(3.2k)

Exams(5)

Science(1.6k)

Important Questions(3.9k)

Entertainment(7)

Ezoicreport this ad

Send feedback

Privacy Policy