Quiz about Tất tần tật về lượng giác

Question 1

sin2a = ?

Accepted Answer

2sina.cosa

Answer

2cos²a.sin²a

Answer

cos²a - sin²a

Answer

sin²a + cos²a

Question 2

sin4a = ?

Accepted Answer

2sin2a.cos2a

Answer

sin2a.cos2a

Answer

4sin2a.cos2a

Answer

4sin2a.cos2a

Question 3

cos4a = ?

Accepted Answer

cos²2a - sin²2a

Answer

2sin2a.cos2a

Answer

2sin2a - 2cos2a

Answer

cos²2a + sin²2a

Question 4

sin8a = ?

Accepted Answer

2sin4a.cos4a

Answer

sin4a.cos4a

Answer

4sin4a.cos4a

Answer

8sin4a.cos4a

Question 5

sin(a + b) = ?

Accepted Answer

sinacosb + sinbcosa

Answer

sinacosa + sinbcosb

Answer

sinasinb + cosacosb

Answer

sinasinb + sinasinb

Question 6

sin(a - b) = ?

Accepted Answer

sinacosb - sinbcosa

Answer

sinasinb - sinbsina

Answer

cosacosb - sinasinb

Answer

sinbcosa - sinacosb

Question 7

cos(a + b) = ?

Accepted Answer

cosacosb - sinasinb

Answer

sinasinb + cosacosb

Answer

sinasinb - cosacosb

Answer

sinacosb - sinbcosa

Question 8

cos(a - b) = ?

Accepted Answer

sinasinb + cosacosb

Answer

sinasinb - cosacosb

Answer

cosacosb - sinasinb

Answer

sinacosb - sinbcosa

Question 9

tan(a + b) = ?

Accepted Answer

$$\frac{ an a+ an b}{1- an a an b}$$

Answer

$$\frac{ an a- an b}{1+ an a an b}$$

Answer

$$\frac{ an a+ an b}{1+ an a an b}$$

Answer

$$\frac{ an a- an b}{1- an a an b}$$

Question 10

tan(a - b) = ?

Accepted Answer

$$\frac{ an a- an b}{1+ an a an b}$$

Answer

$$\frac{ an a+ an b}{1+ an a an b}$$

Answer

$$\frac{ an a- an b}{1- an a an b}$$

Answer

$$\frac{ an a+ an b}{1- an a an b}$$

Question 11

sin3a = ?

Accepted Answer

3sina - 4sin³a

Answer

3sina + 4sin³a

Answer

4sina + 3sin³a

Answer

4sina - 3sin³a

Question 12

cos3a = ?

Accepted Answer

4cos³a - 3cosa

Answer

3cosa - 4cos³a

Answer

4cosa - 3cos³a

Answer

3cos³a - 4cosa

Question 13

cos2a = ?

Accepted Answer

$$\frac{1+\cos2a}{2}$$

Answer

$$\frac{1-\cos2a}{2}$$

Answer

$$\frac{1-\sin2a}{2}$$

Answer

$$\frac{1-\sin2a}{2}$$

Question 14

sin2a = ?

Accepted Answer

$$\frac{1-\cos2a}{2}$$

Answer

$$\frac{1+\cos2a}{2}$$

Answer

$$\frac{1+\sin2a}{2}$$

Answer

$$\frac{1-\sin2a}{2}$$

Question 15

tan2a = ?

Accepted Answer

$$\frac{1-\cos2a}{1+\cos2a}$$

Answer

$$\frac{1+\cos2a}{1-\cos2a}$$

Answer

$$\frac{1-\sin2a}{1+\sin2a}$$

Answer

$$\frac{1+\sin2a}{1-\sin2a}$$

Question 16

sin3a = ?

Accepted Answer

$$\frac{-\sin3a+3\sin a}{4}$$

Answer

$$\frac{-\sin a+3\sin a}{4}$$

Answer

$$\frac{-\sin3a+\sin a}{4}$$

Answer

$$\frac{-\sin3a+3\sin3a}{4}$$

Question 17

cos3a = ?

Accepted Answer

$$\frac{\cos3a+3\cos a}{4}$$

Answer

$$\frac{\cos3a+\cos a}{4}$$

Answer

$$\frac{3\cos a+\cos3a}{4}$$

Answer

$$\frac{3\cos3a+3\cos a}{4}$$

Question 18

sin = 0 <=> ?

Accepted Answer

$$x=k\pi$$

Answer

$$x=\frac{k\pi}{2}$$

Answer

$$x=\frac{\pi}{2}+k\pi$$

Answer

$$x=-\frac{\pi}{2}+k\pi$$

Question 19

sinx = 1 <=> ?

Accepted Answer

$$x=\frac{\pi}{2}+k2\pi$$

Answer

$$x=k\pi$$

Answer

$$x=-\frac{\pi}{2}+k2\pi$$

Answer

$$x=\frac{k\pi}{2}$$

Question 20

sinx = -1 <=> ?

Accepted Answer

$$x=-\frac{\pi}{2}+k2\pi$$

Answer

$$x=k\pi$$

Answer

$$x=\frac{\pi}{2}+k2\pi$$

Answer

$$x=\frac{k\pi}{2}$$

Question 21

cosx = 0 <=> ?

Accepted Answer

$$x=\frac{\pi}{2}+k\pi$$

Answer

$$x=k\pi$$

Answer

$$x=-\frac{\pi}{2}+k\pi$$

Answer

$$x=\frac{k\pi}{2}$$

Question 22

cosx = 1 <=> ?

Accepted Answer

$$x=k2\pi$$

Answer

$$x=\frac{k\pi}{2}$$

Answer

$$x=\frac{\pi}{2}+k\pi$$

Answer

$$x=-\frac{\pi}{2}+k\pi$$

Question 23

cosx = -1 <=> ?

Accepted Answer

$$x=\pi+k2\pi$$

Answer

$$x=k2\pi$$

Answer

$$x=\frac{\pi}{2}+k\pi$$

Answer

$$x=-\frac{\pi}{2}+k\pi$$

Question 24

tanx = 0 <=> ?

Accepted Answer

$$x=k\pi$$

Answer

$$x=\frac{\pi}{4}+k\pi$$

Answer

$$x=-\frac{\pi}{4}+k\pi$$

Answer

$$x=\pi+k\pi$$

Question 25

tanx = 1 <=> ?

Accepted Answer

$$x=\frac{\pi}{4}+k\pi$$

Answer

$$x=k\pi$$

Answer

$$x=-\frac{\pi}{4}+k\pi$$

Answer

$$x=\pi+k\pi$$

Question 26

tanx = -1 <=> ?

Accepted Answer

$$x=-\frac{\pi}{4}+k\pi$$

Answer

$$x=k\pi$$

Answer

$$x=\frac{\pi}{4}+k\pi$$

Answer

$$x=\pi+k\pi$$

Question 27

cotx = 0 <=> ?

Accepted Answer

$$x=\frac{\pi}{2}+k\pi$$

Answer

$$x=k\pi$$

Answer

$$x=\frac{\pi}{4}+k\pi$$

Answer

$$x=-\frac{\pi}{4}+k\pi$$

Question 28

cotx = 1 <=> ?

Accepted Answer

$$x=\frac{\pi}{4}+k\pi$$

Answer

$$x=k\pi$$

Answer

$$x=-\frac{\pi}{4}+k\pi$$

Answer

$$x=\frac{\pi}{2}+k\pi$$

Question 29

cotx = -1 <=> ?

Accepted Answer

$$x=-\frac{\pi}{4}+k\pi$$

Answer

$$x=k\pi$$

Answer

$$x=\frac{\pi}{4}+k\pi$$

Answer

$$x=\frac{\pi}{2}+k\pi$$

Question 30

sina.cosb = ?

Accepted Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)-\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)+\cos\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)-\cos\left(a-b\right)\right]$$

Question 31

cosa.sinb = ?

Accepted Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)-\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)+\cos\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)-\cos\left(a-b\right)\right]$$

Question 32

cosa.cosb = ?

Accepted Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)+\cos\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)-\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)-\cos\left(a-b\right)\right]$$

Question 33

sina.sinb = ?

Accepted Answer

$$-\frac{1}{2}\left[\cos\left(a+b\right)-\cos\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)+\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\sin\left(a+b\right)-\sin\left(a-b\right)\right]$$

Answer

$$\frac{1}{2}\left[\cos\left(a+b\right)+\cos\left(a-b\right)\right]$$

Question 34

sina + sinb = ?

Accepted Answer

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

Answer

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

Answer

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

Answer

$$-2\sin\frac{a+b}{2}\sin\frac{a-b}{2}$$

Question 35

sina - sinb = ?

Accepted Answer

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

Answer

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

Answer

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

Answer

$$-2\sin\frac{a+b}{2}\sin\frac{a-b}{2}$$

Question 36

cosa + cosb = ?

Accepted Answer

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

Answer

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

Answer

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

Answer

$$-2\sin\frac{a+b}{2}\sin\frac{a-b}{2}$$

Question 37

cosa - cosb = ?

Accepted Answer

$$-2\sin\frac{a+b}{2}\sin\frac{a-b}{2}$$

Answer

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

Answer

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

Answer

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

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