Question

Найдите 147cos2a,если cos a=3/7

Answer 1

$147Cos2\alpha=147(2 Cos^{2} \alpha-1)=147[2*( \frac{3}{7}) ^{2}-1]=147(2* \frac{9}{49}-1)=147*( \frac{18}{49}-1)=147*(- \frac{31}{49})=-31*3= -93$

Answer 2

To find the value of 147cos^2(a), we first need to find the value of cos(a). You've given that cos(a) = 3/7. Now, we can use this information to find cos^2(a) and then proceed to find 147cos^2(a).

Step 1: Find cos^2(a) cos^2(a) = (cos(a))^2 = (3/7)^2 = 9/49

Step 2: Find 147cos^2(a) 147cos^2(a) = 147 * (9/49) = 21

So, the value of 147cos^2(a) is 21.