Cos²x + sin2x - 1 = 0, 0° ≤ x ≤ 90°, tan x =

0 and arctan(0.5)

Step-by-step explanation:

if sin2x=2sinx*cosx and 1=sin²x+cos²x, then

cos²x+2sinxcosx-sin²x-cos²x=0;

2sinxcosx-sin²x=0; (to divide by cos²x)

2tanx-tan²x=0;

2 x t divided by n

step-by-step explanation:

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.