Question

2 sin 810° +cos (-90°)+3cos540 °

Answer 1

2sin810=2sin(810-360*2)=2sin90=2*1=2 (Если мы отнимем 360° , значение синуса останется тем же)
cos(-90)=cos90=0 (сos(-x)=cosx)
3cos540=3cos(540-360)=3cos180=3*1=3 (Если мы отнимем 360° , значение косинуса останется тем же)
Суммируем:
2 sin 810° +cos (-90°)+3cos540 °=2+0+3=5

Answer 2

To calculate the value of the expression:

2sin(810°) + cos(-90°) + 3cos(540°)

You can simplify it step by step:

1. Start with 2sin(810°): Since the sine function has a periodicity of 360°, you can subtract multiples of 360° from the angle to find an equivalent angle between 0° and 360°: 810° - 2 * 360° = 90° So, 2sin(810°) is equal to 2sin(90°), and the sine of 90° is 1. 2 * 1 = 2

2. Moving on to cos(-90°): The cosine of -90° is the same as the cosine of 90° because the cosine function is an even function, which means it's symmetric about the y-axis. So, cos(-90°) = cos(90°) = 0

3. Finally, for 3cos(540°): Like in the first step, you can simplify the angle: 540° - 1 * 360° = 180° So, 3cos(540°) is equal to 3cos(180°), and the cosine of 180° is -1. 3 * (-1) = -3

Now, you can add these values together:

2 + 0 - 3 = -1

So, the value of the expression 2sin(810°) + cos(-90°) + 3cos(540°) is -1.