4(2x +5) = (8x + 20)
8x =20 is an equivalent expression
Angle a is 35 degrees angle b is 55 degrees angle c is 110 degrees
Answer:
135° and 225°
Step-by-step explanation:
basically you want to find the value of x between 0 and 360 in this equation
cos x/2 = -(√2)/2
assume x/2 as n, so
cos n = -(√2)/2
n = 45°
then remember the quadrant system
0-90 1st quadrant, all is POSITIVE
90-180 2nd quadrant, only SIN has positive value
180 - 270 3rd quadrant, only TAN has positive value
270 -360 4th quadrant, only COS positive here.
so if you try to find negative value look into 2nd and 3rd quadrant that related 45° to x-axis (0°or 180°)
so the value of x is
180 - 45 = 135° (2nd quadrant) and
180 + 45° = 225° (3rd quadrant)
