Question

if cos(a+b)=0 then cos (a-b) =-1 find A and B​

Answer 1

cos(A+B)= 0

But cos 90 = 0

Therefore, A+B= 90................................(i)

cos(A-B)= 1

But, cos 0= 1

Therefore, A-B = 0..................................(ii)

From (i) and (ii),

90-A= A- 0

90= 2A

45=A

Therefore, A= 45 and  B= 45

Hope it helps

Answer 2

Answer:

The value of a and b is 45

Step-by-step explanation:

cos(a + b) = 0

Since cos 90 = 0

Hence,

cos(a + b) = cos 90

Or,

a + b = 90 ________[1]

Now given that,

cos(a - b) = -1

Hence,

cos(b - a) = 1

Since, cos 0 = 1

Hence,

cos(b - a) = cos 0

Or

b - a = 0 _________[2]

Adding [1] and [2]

a + b + (b - a) = 90 + 0

→ a + b + b - a = 90

→ 2b = 90

→ b = 90/2

→ b = 45

From [1]

a + b = 90

Substituting the value of b

→ a + 45 = 90

→ a = 90 - 45

→ a = 45

Hence,

a = b = 45