Question

Solve as fast as you can​

Answer 1

here

1)

cos(alpha)=(point on x-axis)/(a^2+c^2)^1/2

cos(beta)=(point on y-axis)/(a^2+b^2)^1/2

cos(gama)=(point on z-axis)/(b^2+c^2)^1/2

{clearly u can visualize using figure,if can't be able to understand it with imagination}

2) cos^2(alpha)+cos^2(beta)+cos^2(gama)=

a^2/(a^2+c^2) +b^2/(a^2+b^2) +c^2/(b^2+c^2)

={a^2/(a^2+b^2)(b^2+c^2) +b^2/(a^2+c^2)(b^2+c^2)+c^2/(b^2+a^2)(a^2+c^2)}/(a^2+b^2)(a^2+c^2)(c^2+b^2)

, solving it.we get

value=1