Adding negative numbers
7+(-7)=

0

Step-by-step explanation:

Follow the signs rule:

IF:

There is a + sign, and the number directly next is +, add

There is a + sign, and the number directly next is -, subtract

There is a - sign, and the number directly next is +, subtract

There is a - sign, and the number directly next is -, add

In this case, there is a positive & a negative sign, so the sign is negative. Subtract:

7 + (-7) = 7 - 7 = 0

0 is your answer.

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Third option is correct.

Step-by-step explanation:

since we have given that

Length of first string = 43 cm

Angle of elevation with the horizontal = 50°

Length of second string = 35 cm

Angle of elevation with the horizontal = 70°

We need to find the distance between the points of suspension of the strings on the ceiling .

WE will use "Cosine Law".

In ΔABC,

Similarly,

In ΔPCR,

So, Total distance between the points of suspension of the strings on the ceiling is given by

Hence, third option is correct.