1. Công thức lượng giác

1. Công thức lượng giác

by Phong Lê

Multiple Choice

$$30^o=.....rad$$  

• $$\frac{\pi}{6}$$  

• $$\frac{\pi}{3}$$  

• $$\frac{\pi}{4}$$  

• $$\frac{\pi}{2}$$  

Multiple Select

sin(a+b)=?

• sina.sinb + cosa.cosb

• sina.cosb + cosa.sinb

• sina.cosb - cosa.sinb

• sina.sinb - cosa.cosb

Multiple Choice

cos(a-b)=?

• cosa.sinb - sina.cosb

• cosa.sinb - sina.cosb

• cosa.cosb + sina.sinb

• cosa.sinb + sina.cosb

Multiple Choice

2sina.cosa=

• sin2a

• cos2a

• tan2a

• cot2a

Multiple Choice

cos2a=?

• 2sin²a-1

• 1-2cos²a

• 1-sin²a

• cos²a-sin²a

Multiple Choice

cos a +cosb=?

• 2cos $$\frac{a+b}{2}$$ cos $$\frac{a-b}{2}$$

• 2sinundefined cosundefined

• 2cosundefined sinundefined

• 2sinundefined sinundefined

Multiple Choice

$$\frac{1}{2}$$  (sin(a+b)+sin(a-b))=?

• sina.sinb

• cosa.sinb

• sina.cosb

• cosa.cosb

Multiple Choice

sina + cos a =?

• $$\sqrt{2}$$ sin( x - $$\frac{\pi}{4}$$ )

• undefined sin( x +undefined )

• undefined cos( x -undefined )

• undefined cos( x +undefined )

Multiple Choice

Tìm công thức SAI:

• $$\sin^2a+\cos^2a=1$$

• $$1+\tan^2a=\frac{1}{\cos^2a}$$

• $$1+\cot^2a=\frac{1}{\sin^2a}$$

• $$\tan a+\cot a=1$$

Multiple Choice

$$\frac{2\pi}{3}=....$$  

• $$30^o$$  

• $$45^o$$  

• $$60^o$$  

• $$120^o$$  

Multiple Choice

$$\cos\frac{37\pi}{12}=?$$  

• $$\frac{\sqrt{6}+\sqrt{2}}{4}$$  

• $$\frac{\sqrt{6}-\sqrt{2}}{4}$$  

• $$-\frac{\sqrt{6}+\sqrt{2}}{4}$$  

• $$\frac{\sqrt{2}-\sqrt{6}}{4}$$  

Multiple Choice

$$\sin45^o=....$$  

• $$\frac{1}{2}$$  

• $$\sqrt{2}$$  

• $$\frac{\sqrt{2}}{2}$$  

• $$-\sqrt{2}$$  

Multiple Choice

$$\tan2x=...$$  

• $$\frac{\sin x}{\cos x}$$  

• $$\frac{\sin a}{\cos a}$$  

• $$\frac{\sin2x}{\cos2x}$$  

• $$\frac{\sin2a}{\cos2a}$$  

Multiple Choice

Chọn đẳng thức đúng ?

• $$\sin^2x-\cos^2x=1$$

• $$\sin^2x+\cos^2x=1$$

• $$\sin^2x=1+\cos^2x$$

• $$\cos^2x=\sin^2x-1$$

Multiple Choice

Chọn đẳng thức đúng ?

• $$1+\cos^2x=\frac{1}{\tan^2x}$$

• $$1-\cos^2x=\frac{1}{\tan^2x}$$

• $$1+\tan^2x=\frac{1}{\cos^2x}$$

• $$1-\tan^2x=\frac{1}{\cos^2x}$$

Multiple Choice

Công thức nào ĐÚNG?

• $$\cos\left(a+b\right)=\cos a.\cos b+\sin a.\sin b$$

• $$\cos\left(a+b\right)=\cos a.\cos b-\sin a.\sin b$$

• $$\cos\left(a+b\right)=\sin a.\cos b+\cos a.\sin b$$

• $$\cos\left(a+b\right)=\sin a.\cos b-\cos a.\sin b$$

Multiple Choice

Chọn câu đúng ?

• $$\sin\left(a-b\right)=\cos a.\cos b-\sin a.\sin b$$  

• $$\sin\left(a-b\right)=\cos a.\cos b+\sin a.\sin b$$

• $$\sin\left(a-b\right)=\sin a.\cos b-\cos a.\sin b$$

• $$\sin\left(a-b\right)=\sin a.\cos b+\cos a.\sin b$$

Multiple Choice

$$\sin4a=....$$  

• $$2.\sin a.\cos a$$  

• $$2.\sin2a.\cos2a$$  

• $$2.\sin4a.\cos4a$$  

• $$1-\cos^24a$$  

Multiple Choice

Chọn câu SAI ?

• $$\cos2a=2\cos^2a-1$$

• $$\cos2a=1-2\sin^2a$$

• $$\cos2a=\sin^2a-\cos^2a$$

• $$\cos2a=\cos^2a-\sin^2a$$

Multiple Choice

$$\cos6a-\cos2a=....$$  

• $$2\cos4a.\cos2a$$  

• $$2\cos8a.\cos4a$$  

• $$2\sin8a.\sin4a$$  

• $$-2\sin4a.\sin2a$$