class 10 Introduction to trigonometry

which of the following is correct

• $1\ -\ \tan\ ^2\ A\ =\ \sec^2\ A$

• $\sin^2\ A\ +1\ =\ \cos^2\ A$

• $1-\ \operatorname{cosec}^2\ A\ =\ -\cot^2\ A$

• none is correct

sin 30 cos 60 + cos 30 sin 60 =

• sin 0

• cos 0

• cos 90

• sin 90

cos 30 cos 60 - sin 30 sin 60

• cos 0

• cos 30

• cos 60

• cos 90

which of the following is not defined

• sec 30

• cosec 30

• cot 45

• All are defined

which option is correct

• tan A = 1/ cosec A

• sin (90-A) = Sec A

• $\sin^2\ A\ +\ Sin^2\ \left(90-A\ \right)=\ 1$

• All are incorrect

If sin A= 3 / 5 , find tan A  $\times$  cos A

• 4/5

• 3/4

• 4/3

• 3/5

If tan A = 4/3, sec A= ?

• 5/3

• 3/5

• 3/4

• none of these

 $1-\frac{\cot^{2\ }45}{\sin\ 30}$  = ?

• 1

• -1

• 2

• 0

If sin (A-B) = 1/2 and and cos (A+B) = 1/2 find A and B

• `A= 15 and B= 45

• A= 45 and B= 15

• A= 45 and B= 30

• none of these

 $\frac{1+\tan^2A}{1+\cot^2A}=?$  

• 1

•  $\tan^2A$  

•  $\cot^2A$  

• tan A