True and False
Q1: cosA = 4/3 for some angle A.
Ans: Flase
Q2: tanA = sinA/cosA
Ans: True
Q3: secA = 1cosA, for an acute angle
Ans: True
Q4: sin60º = 2sin30º
Ans: Flase
Q5: SinA + CosA = 1
Ans: Flase
Short Answer Questions
Q6: Write the values cos 0°, cos 45°, cos 60° and cos 90°. What happens to the values of cos as angle increases from 0° to 90°?
Ans: cos0^{∘} = 1
cos45^{∘} = 1/√2
cos 60^{∘} = 1/2
cos 90^{∘ }= 0
We can see that values of cos decreases as angle increases from 0° to 90°
Q7: Write the values of tan 0°,tan 30°, tan 45°, tan 60° and tan 90°. What happens to the values of tan as angle increases from 0° to 90°?
Ans: tan 0^{∘} = 0
tan 30^{∘} = 1/√3
tan 60^{∘} = √3
cos 90^{∘ }= undefind
We can see that values of cos decreases as angle increases from 0° to 90°
Q8: If cosec A = √10 . find other five trigonometric ratios.
Ans: Given cosec A = √10
Now By Pythagoras theorem
Q9: The value of (sin 30^{∘} + cos 30^{∘}) − (sin 60^{∘} + cos 60^{∘}) is
Ans:
Q10: Evaluate the following: 2sin^{2} 30^{∘} − 3cos^{2}45^{∘} + tan^{2}60^{∘}
Ans:
Q11: Evaluate:
cot^{2}30^{∘ }− 2cos^{2}60^{∘} − 3/4sec^{2}45^{∘} − 4sec^{2}30^{∘}
^{Ans:}
^{}
Q12: Write the values of sin 0°, sin 30°, sin 45°, sin 60° and sin 90°. What happens to the values of sin as angle increases from 0° to 90°?
Ans:
We can see that values of sin increases as angle increases from 0° to 90°
Q13: If sin A = 3/5 .find cos A and tan A.
Ans:
Now By Pythagoras theorem
Q14: In a right triangle ABC right angled at B if sinA = 3/5. find all the six trigonometric ratios of C.
Ans:
Now By Pythagoras theorem
Q15: If sinB = 1/2 , show that 3 cosB − 4 cos^{3}B = 0
Ans:
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