Question

tell the correct answer​

Answer 1

Step-by-step explanation:

$sin {}^{2}a + cos {}^{2}a = 1 \\ (\frac{3}{4} )^2a + cos {}^{2}a = 1 \\ \frac{9}{16} a + cos {}^{2} a = 1 \\ cos {}^{2} a = \frac{16 + 9}{16} \\ cos \: a = \sqrt{ \frac{25}{16} } \\ cos \: a = \frac{5}{4} .$.

:)

Answer 2

Answer:

cosA = √7/4

Step-by-step explanation:

Given,

sinA = (3/4)

On squaring both sides, we get

sin²A = (9/16)

[∵ sin²A + cos²A = 1]

⇒ (9/16) + cos²A = 1

⇒ cos²A = 1 - (9/16)

⇒ cos²A = (16 - 9)/16

⇒ cos²A = 7/16

⇒ cosA = √7/4

Hope it helps!