Answer:
The length of rectangular panel is 6.4 cm.
Step-by-step explanation:
We are given the following information in the question:
Area of rectangular solar panel = 128 square cm
Width of panel = 20 cm
We have to find the length of the panel
Formula:

Hence, the length of rectangular panel is 6.4 cm.
This is an example of direct variation as greater would be length and breadth, the greater would be the area.
2x + 22 = 4(x + 3)...distribute thru the parenthesis
2x + 22 = 4x + 12...subtract 2x from both sides, subtract 12 from both sides
22 - 12 = 4x - 2x...simplify
10 = 2x...divide both sides by 2
10/2 = x...reduce
5 = x <==
When dividing two terms with the same base, subtract the exponent in the denominator from the exponent in the numerator: Power of a Power: To raise a power to a power, multiply theexponents.
Let a =107° and b=42°;
So cos 107° cos 42° + sin 107° sin 42° = cosa.cos42 + sina.sinb = cos(a-b)
and cos 107° cos 42° + sin 107° sin 42° = cos(107-42) = cos(65°)