Trigonometry Question?
回答 (3)
2020-06-22 2:58 pm
Trigonometric identities used:
sin(A ± B) = sinA cosB ± cosA sinB
2 sin56° cos88°
= 2 sin56° cos88° + cos56° sin88° - cos56° sin88°
= (sin56° cos88° + cos56° sin88°) + (sin56° cos88° - cos56° sin88°)
= sin(56° + 88°) + sin(56° - 88°)
= sin144° + sin(-32°)
= sin(180° - 36°) + (-sin32°)
= sin36° - sin32°
The answer: sin36 - sin32
sin(A ± B) = sinA cosB ± cosA sinB
2 sin56° cos88°
= 2 sin56° cos88° + cos56° sin88° - cos56° sin88°
= (sin56° cos88° + cos56° sin88°) + (sin56° cos88° - cos56° sin88°)
= sin(56° + 88°) + sin(56° - 88°)
= sin144° + sin(-32°)
= sin(180° - 36°) + (-sin32°)
= sin36° - sin32°
The answer: sin36 - sin32
2020-06-22 2:56 pm
2 * sin(a) * cos(b) =>
sin(a) * cos(b) + sin(a) * cos(b) =>
sin(a)cos(b) + sin(b)cos(a) + sin(a)cos(b) - sin(b)cos(a) =>
sin(a + b) + sin(a - b)
2sin(56)cos(88) =>
sin(56 + 88) + sin(56 - 88) =>
sin(144) + sin(-32) =>
sin(144) - sin(32)
That's all you need to do. You don't have to evaluate anything.
sin(a) * cos(b) + sin(a) * cos(b) =>
sin(a)cos(b) + sin(b)cos(a) + sin(a)cos(b) - sin(b)cos(a) =>
sin(a + b) + sin(a - b)
2sin(56)cos(88) =>
sin(56 + 88) + sin(56 - 88) =>
sin(144) + sin(-32) =>
sin(144) - sin(32)
That's all you need to do. You don't have to evaluate anything.
2020-06-22 10:36 pm
There is a formula : 2 sin A cos B = sin (A + B) + sin (A - B)
If A = 56° and B = 88°, ----
=> 2 sin 56° * cos 88° = sin (56°+88°) + sin (56°- 88°)
=> sin (144°) + sin ( - 32°) =====>>> Remember : sin ( - x ) = - sin x
=> sin (π-36) - sin 32
=> sin 36 - sin 32 .................... Answer
If A = 56° and B = 88°, ----
=> 2 sin 56° * cos 88° = sin (56°+88°) + sin (56°- 88°)
=> sin (144°) + sin ( - 32°) =====>>> Remember : sin ( - x ) = - sin x
=> sin (π-36) - sin 32
=> sin 36 - sin 32 .................... Answer
收錄日期: 2021-04-18 18:31:49
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