Test: Complementary Angles of Trigonometry - Grade 9 MCQ

cos²17-sin²73
=cos²17-sin²(90-17)
=cos²17-co^s217   (because sin(90-x)=cos x)
=0

Taking LCM

Explanation:

- Given expression: cos θ cos(90° - θ) – sin θ sin (90° - θ)
- We know that cos(90° - θ) = sin θ and sin(90° - θ) = cos θ
- Substitute these values into the expression:
= cos θ * sin θ - sin θ * cos θ
= sin θ cos θ - sin θ cos θ
= 0
- Therefore, the value of the expression is 0.

we know sin(90 - a) = cos(a) 

cos(90 - a) = sin(a)

sin(a) = 1/cosec(a)

sec(a) = 1/cos(a)

cos40 = cos(90-50) = sin50

cosec40 = cosec(90-50) = sec50

so our expression becomes

sin50/sin50 + sec50/sec50 - 4cos50 / sin40

= 1 + 1 - 4(1)   since cos50 = sin40

= -2

cos(θ)=sin(90-θ)
so 40+A+30=90
A=20

Taking LCM

We need to simplify the following expression:

Step 1: Simplify Each Term

For   :

• Note that , because .
• Therefore, .

For  :

• Note that , because .
  Therefore, .

Step 2: Substitute and Simplify

Now, substituting these simplified values back into the original expression:

1 + 1 - 2 = 2 - 2 = 0

Final Answer:

The correct answer is:

c) 0

tan 1.tan 2.tan 3...tan (90 - 3 ).tan ( 90 - 2 ).tan ( 90 - 1) 
=tan 1.tan 2 .tan 3...cot 3.cot 2.cot 1 
=tan 1.cot 1.tan 2.cot 2.tan 3.cot 3 ... tan 89.cot 89 
1 x 1 x 1 x 1 x ... x 1 =1

Explanation:

Ratio of Complementary Angles:

- Complementary angles are two angles that add up to 90 degrees.
- The ratio of complementary angles is the ratio of the measures of the two angles that add up to 90 degrees.

Given:
Let the two complementary angles be x and y.

Therefore:
x + y = 90

Ratio of Complementary Angles:
The ratio of the two angles can be represented as:
x:y

Using the given information:
x + y = 90
x = 90 - y

Substitute x in the ratio:
(90 - y) : y

Simplify the ratio:
90 : y

Therefore:
The ratio of the two complementary angles is 90 : y.

Conclusion:
Since the ratio of complementary angles is 90 : y, the value of y is 1.

Answer:
C: 1