Pls answer ASAP I need by end of day #1

Step-by-step explanation:

∠A+∠B=90 complementary angles ( the sum equal 90°)

∠A=90 degrees-∠B

tan A=sinA/cos A

AB²= AC² +BC² (Pythagorean theorem)

if angle A=angle B then the angles are 45 degrees

cos A=sin(90-A)  

sin (a - b) = sin a.cos b - sin b.cos a

sin(90-A)=sin90.cosA-sinbAcos90 cos 90=0 and sin 90=1

sin(90-A)=1*cosA

sin(90-A)=cosA

the ones are  in bold are right