Нужно знать:
sin30° = 1/2; sin 45° = √2/2; sin60° = √3/2;
cos45° = √2/2; cos60° = 1/2;
tg45° = 1; ctg60° = √3/3.
Поэтому:
1) 2sin30° + 2соѕ45° = 2 ·1/2 + 2 · √2/2 = 1 + √2;
2) 3sin60°- 2cos60° = 3 · √3/2 - 2 · 1/2 = 3√3/2 - 1;
3) sin30° - Зtg45° = 1/2 - 3 · 1 = 0,5 - 3 = -2,5;
4) sin45° + 2сtg60° = √2/2 + 2 · √3/3 = (3√2 + 4√3)/6.
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Нужно знать:
sin30° = 1/2; sin 45° = √2/2; sin60° = √3/2;
cos45° = √2/2; cos60° = 1/2;
tg45° = 1; ctg60° = √3/3.
Поэтому:
1) 2sin30° + 2соѕ45° = 2 ·1/2 + 2 · √2/2 = 1 + √2;
2) 3sin60°- 2cos60° = 3 · √3/2 - 2 · 1/2 = 3√3/2 - 1;
3) sin30° - Зtg45° = 1/2 - 3 · 1 = 0,5 - 3 = -2,5;
4) sin45° + 2сtg60° = √2/2 + 2 · √3/3 = (3√2 + 4√3)/6.