Question

Pls Answer This for 21 points​

Answer 1

Answer:

There are two types of water hardness, temporary and permanent.

Temporary Hardness is due to the bicarbonate ion, HCO3-, being present in the water. This type of hardness can be removed by boiling the water to expel the CO2, as indicated by the following equation:

Ca(HCO3)2 →← CaCO3 + CO2 + H2O

Permanent hardness is due to calcium and magnesium nitrates, sulphates, and chlorides etc. This type of hardness cannot be eliminated by boiling.

Step-by-step explanation:

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Answer 2

L.H.S.

(1+tan²a) + (1+ $\frac{1}{tan²a}$)

=> (1+$\frac{sin²a}{cos²a}$) + (1+ $\frac{cos²a}{sin²a}$)

=> ($\frac{cos²a+sin²a}{sin²a}$) + ( $\frac{sin²a+cos²a}{sin²a}$)

=> ( $\frac{1}{cos²a}$) + ( $\frac{1}{sin²a}$)

=> $\frac{1}{cos²a}$ + $\frac{1}{sin²a}$

=> $\frac{sin²a+cos²a}{cos²a×sin²a}$

=> $\frac{1}{(1-sin²a)×sin²a}$

=> $\frac{1}{sin²a - sin⁴a}$ = R.H.S.

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