Answer:
27 Chickens
Step-by-step explanation:
<em>Represent the chicken with A and the cows with B</em>
Given
A has 2 legs and B has 4; So:
Required
Determine A and B
Make B the subject of formula in the first equation
Substitute 30 - A for B in the second equation
Open the bracket
Collect Like Terms
Divide through by -2
<em>Hence, the farmer has 27 chickens</em>
A positive × A negative = Negative
A positive × A positive = Positve
A negative × A negative = Positive
Answer:
cos 78⁰.
Step-by-step explanation:
Use cos 2A = cos^2 A - sin^2 A
so cos^2 39 - sin^2 39 = cos (2*39) = cos 78.