Solve sqrt{42^2-21^2}

$$\sqrt { 42 ^ { 2 } - 21 ^ { 2 } }$$

Evaluate

$$21\sqrt{3}\approx 36.373066959$$

Solution Steps

Calculate 42 to the power of 2 and get 1764.

$$\sqrt{1764-21^{2}}$$

Calculate 21 to the power of 2 and get 441.

$$\sqrt{1764-441}$$

Subtract 441 from 1764 to get 1323.

$$\sqrt{1323}$$

Factor 1323=21^{2}\times 3. Rewrite the square root of the product \sqrt{21^{2}\times 3} as the product of square roots \sqrt{21^{2}}\sqrt{3}. Take the square root of 21^{2}.

$$21\sqrt{3}$$