ANSWER
![a. \: \: \: ( 1,0)](https://img.qammunity.org/2020/formulas/mathematics/high-school/6lo22w0dwhxe7wofwz7u4rod09qi6w3237.png)
![b. \: \: \: (0,1)](https://img.qammunity.org/2020/formulas/mathematics/high-school/rnrecsc7qiw5kesuasjpqlbvkrtme3iwpr.png)
EXPLANATION
a. We want to find the coordinates on the unit circle that corresponds to an angle of 0°
In general, the points on the unit circle are given by,
![( \cos( \theta) ,\sin( \theta))](https://img.qammunity.org/2020/formulas/mathematics/high-school/8il9tkkka92ahgzvbdp4c70qtjphmorhwp.png)
So we substitute,
![\theta = 0 \degree](https://img.qammunity.org/2020/formulas/mathematics/high-school/g2798x9u7oxwxl4gomtrm4y5fxnee05a6q.png)
to obtain,
![( \cos( 0\degree) ,\sin( 0\degree))](https://img.qammunity.org/2020/formulas/mathematics/high-school/ya3w2wctcdsxhcizvp40i8es7z419aq2eb.png)
![( 1,0)](https://img.qammunity.org/2020/formulas/mathematics/high-school/2nfj0n23e927y8cnpm8so1udg2ih4rhhs9.png)
b. For the coordinates of the point on the unit circle that corresponds to an angle of 90º,
We substitute
![\theta = 90 \degree](https://img.qammunity.org/2020/formulas/mathematics/high-school/n7xpm8l70xkfuqzg08q8nj618hxtufcmck.png)
to obtain,
![( \cos( 90\degree) ,\sin( 90\degree))](https://img.qammunity.org/2020/formulas/mathematics/high-school/q5sxcymaowkm5wa3dlnfwyhltctbfonmdr.png)
This simplifies to,
![( 0 ,1)](https://img.qammunity.org/2020/formulas/mathematics/high-school/ljo1jpk3hgu1e6n473idjw5kit054kt269.png)