Question

Find the value of the following
expression
15 cos? 0° + 3 sin2 90° – 8 cos? 60° + 9 sec2 30°
--------------------------------------------
2 cot? 45° – 3 tan? 60° + 5 cos 0°
(1) 14
(2) - 14
(3) 28
(4) – 28​

Answer 1

Answer:

15 cos² 0° + 3 sin² 90° - 8 cos² 60° + 9 sec² 30°

____________________________________

2 cot² 45° - 3 tan² 60° + 5 cos 0°

= -14

So, Ans → (2) -14

Step-by-step explanation:

cos 0° = 1

sin 90° = 1

cos 60° = ½

sec 30° = 2/√3

cot 45° = 1

tan 60° = √3

Putting these Values in the Problem to obtain the Required Answer

15 cos² 0° + 3 sin² 90° - 8 cos² 60° + 9 sec² 30°

____________________________________

2 cot² 45° - 3 tan² 60° + 5 cos 0°

= 15 (1)² + 3 (1)² - 8 (½)² + 9 (2/√3)²

_________________________

2 (1)² - 3 (√3)² + 5 (1)

= 15 (1) + 3 (1) - 8 (¼) + 9 (4/3)

____________________

2 (1) - 3 (3) + 5

= 15 + 3 - 2 + 3 (4)

____________

2 - 9 + 5

= 15 + 3 - 2 + 12

___________

-2

= 28

__

-2

= -14