Solve cos70^circcos10^circ-cos20^circcos80^circ

$$\cos 70 ^ { \circ } \cos 10 ^ { \circ } - \cos 20 ^ { \circ } \cos 80 ^ { \circ }$$

Evaluate

$$0.173648177666930334256218953275956$$

Solution Steps

Evaluate trigonometric functions in the problem

$$0.3420201433256688 \cdot 0.984807753012208 - 0.9396926207859084 \cdot 0.17364817766693041$$

Multiply 0.3420201433256688 and 0.984807753012208 to get 0.3368240888334652200599261647104.

$$0.3368240888334652200599261647104-0.9396926207859084\times 0.17364817766693041$$

Multiply 0.9396926207859084 and 0.17364817766693041 to get 0.163175911166534885803707211434444.

$$0.3368240888334652200599261647104-0.163175911166534885803707211434444$$

Subtract 0.163175911166534885803707211434444 from 0.3368240888334652200599261647104 to get 0.173648177666930334256218953275956.

$$0.173648177666930334256218953275956$$

Factor

$$\frac{3 \cdot 11149 \cdot 1297935372880455154843625387}{2 ^ {31} \cdot 5 ^ {33}} = 0.17364817766693036$$