Question

please answer it plese

Answer 1

Answer:

Step-by-step explanation:

1) suppose A is an acute angle.

cos A = 0.6 ---> (cos A)^2 = 0.36

---> (sin A)^2 = 1 - (cos A)^2 = 1 - 0.36

= 0.64

---> sin A = 0.8

---> tan A = sin A / cos A = 0.8 / 0.6

= 8 / 6 = 4 / 3.

5 sin A - 3 tan A = 5 × 0.8 - 3 × 4 / 3

= 4 - 4 = 0.

thus 3) 0 is the right answer.

2) x = a cos O , y = a sin O, then

x^2 = a^2(cos O)^2

and

y^2 = a^2(sin O)^2

then

x^2 + y^2 = a^2((cos O)^2 + (sin O)^2)

= a^2 × 1 = a^2.

thus 1) x^2 + y^2 = a^2 is the right answer.

3) cos 315° = cos(360° - 45°)

= cos(- 45°) = cos 45°

= 1 / sqrt(2)

thus 1) 1 / sqrt(2) is the right answer.